Sydonay

Sydonay (シュドナイ) is part of Bal Masqué's Trinity and a powerful Crimson Lord. His true name is "Thousand Changes" or "Transformation" (千変). In the past, he referred to himself as Chi You (蚩尤), where he once defeated various Flame Haze from different parts of the world. Later, he returns to his post as part of the Trinity, garnering the title "General" (将軍), and assists the remaining members of the organization in their mission to extract and retrieve the Reiji Maigo, and later, free the Snake of the Festival.

Appearance
Sydonay is a tall, well-built man of a fair complexion who usually wears a pair of dark sunglasses and brown-colored suits, matched with a pair of trousers and leather shoes. Underneath his suit, he wears a khaki-colored shirt. Sydonay has short, grey hair, which he slicks back on his head, with fours strands falling down evenly on his forehead. He has a chiseled face, with a thick nose and clearly defined cheekbones and brow ridge. He has thick eyebrows that spike out at the ends. Sydonay usually doesn't take off his sunglasses, but has purple irises. He always presents himself in a laid-back manner, and is often seen smoking. In the Great War, he wore a complete suit of armor.

Personality
He has a valorous personality, even liberating his subordinates, and has many friends (including Sokar). If anything dangerous happens to his beloved Hecate, he rages furiously, attacking whoever is in his surroundings no matter friend or foe.

For some time, Sydonay stayed outside of the Bal Masqué organization, because he wanted the freedom to do as he wanted, such as serving the Denizens as a bodyguard for his personal hobby. He also appreciates human civilization enough to enjoy smoking cigarettes. Out of the Trinity, he cares for Hecate the most, coming to her rescue even when in a fight as shown during his battle with Margery as he abandons the battle to save her from the burning flames.

Background
In the past, Sydonay once used the name Chi You (蚩尤), the name of a war deity who waged war against the Yellow Emperor but was eventually defeated and executed. Ironically, his ultimate adversary is Yu Xuan's contracted Crimson Lord, "Pennant of Offering" Di Hong ("奉の錦旆" 帝鴻), which is the other name for the Yellow Emperor. Di Hong's divine vessel is also called "Kun Wu" (昆吾), named after Yellow Emperor's sword.

Kun Wu, which, according to the legend, could cut through jade like paper, and was used to kill Chi You. It is hinted that Di Hong and Chi You (Sydonay) have fought with each other in ancient times. But in the end, contradictory to the factual legend, in the battle at Shanghai's Outlaw branch, Sydonay personally executed Yu Xuan and drove Di Hong back to the Crimson Realm.

While he was with Bal Masqué, Sydonay received missions to kill notable Flame Haze, namely Karl Berwald and Yu Xuan. With his weapon, Shintetsu Nyoi in hand, he leads an army of Denizens and Lords, destroying the major Outlaws throughout Europe and China.

Aizen Siblings Arc
Sydonay acts as a bodyguard for the "Aizen Siblings" as they come to Misaki City. He watches from above as Tiriel and Sorath kiss in an alley.

The next day, Sydonay walks the streets of the city with Sorath and Tiriel, with all of the citizens looking at the siblings. He comments that their costumes and kissing are causing the unwanted attention, making Tiriel remind him that he is under the protection of her Cradle Garden. She activates it, explaining to Sydonay that she is helping her brother find what he is searching for. She also shows him her Treasure Tool, Orgel. The group are later at an outdoor café, where Sydonay is bothered by the siblings' kissing. Tiriel notes that something is bothering Sydonay, and he tells them that he senses two Flame Haze, but Tiriel wants to greet them. They start walking down the street and passing Margery Daw, Keisaku and Eita. Sydonay converses with Margery and introduces her to Tiriel. Sydonay and the siblings leave after Sorath claims that Margery doesn't have what he wants. They keep walking into the night, as Sorath asks where the Nietono no Shana is.

In a park with Cradle Garden activated, Tiriel and Sydonay drink tea at a table. Sydonay is told to protect the Orgel while the siblings take the Nietono no Shana. He warns that Margery will intervene, but Tiriel claims that they are invincible in Cradle Garden.

Sydonay sits in a car and protects the Orgel when he is contacted by Tiriel. She wants him to eliminated Margery, who was destroying her Pinions, but Sydonay wants to leave her alone. He eventually agrees because his job is to protect the siblings from the Flame Haze. He gets out of the car and faces off with Margery before transforming into his Manticore form and attacking. He is able to snatch Margery in mid-air because she is unable to chant poems and doesn't have the will to fight. He throws her into a building and blasts her with a ball of Power of Existence. He flies away, but notices Yūji moving on the bridge and asks if he is a Mystes. Sydonay pins Yūji to the bridge and shows him his human appearance, before reaching inside him to take his Treasure Tool. He figures out which Treasure Tool it is before being attacked by Margery in werewolf form. Sydonay is surprised she survived their earlier encounter, but is attacked again by balls of Margery's existence, causing him to fall in the river. Margery makes clones and circles Sydonay, before attacking again. He looks up at the bridge to check on the "Aizen Siblings" and sees the flames of the "Flame-Haired Burning-Eyed Hunter". He concludes that the "Aizen Siblings" will die and transforms into his Snake form, fleeing the battle.

Mathilde's Successor Arc
At Seireiden, Sydonay sits in a room with Bel Peol and Hecate and tells them that Yūji has the Reiji Maigo inside him.

Misago Festival Arc
At Seireiden, Sydonay looks out the window, commenting to Bel Peol that the place is empty. Bel Peol says that they will make the Seireiden a container for the Reiji Maigo and Hecate, with Hecate agreeing to the plan. Sydonay wants the plan to not put Hecate in danger, with Bel Peol saying that she will become an "eternal existence". Later, the two see a flame, which allows the "Seeking Researcher" Dantalion to contact them. Dantalion tells them that preparations are underway.

The Synchronization Campaign Arc
In a church room at Seireiden, Sydonay is with Hecate and asks her what's wrong. She responds that Seireiden is shaking. He mentions a blue insignia and tells her that she will be busy soon while she is praying, so Sydonay tells her to wish upon him and asks what she wants. She wants an answer to what she seeks. She won't tell him what she seeks and makes Sydonay confused when Bel Peol enters. Bel Peol says that Hecate isn't seeking anything but will be sought after when the blue insignia is activated. She again states to Sydonay that Hecate will become an "eternal existence", with a vast amount of Power of Existence. Sydonay claims that he will protect Hecate. Later, a Fūzetsu is placed in Misaki City, when the gold birds from the Misago Festival were being burned, with Seireiden descending near the ground. Bel Peol leaves and confronts Wilhelmina, which causes her to attack the Reiji Maigo and Yūji, only to be blocked by Sydonay. He reaches for Yūji, but Wilhelmina attacks again with a javelin made of ribbons. Shana protects Yūji and is impaled by the javelin, allowing Sydonay to take Yūji and return to Seireiden in Manticore form.

Back at Seireiden, Sydonay asks Hecate if it was alright to capture Yūji so that she can synchronize with him, which she doesn't mind. Bel Peol teases him for worrying and says that Hecate will fulfill the Power of Existence, with the fulfillment being what is bothering Sydonay. Bel Peol reassures him that Hecate's purity will be vital for the blue insignia. Later, Sydonay and the rest of the Trinity are in the Seireiden engine room and watch Yūji, who is frozen in a statue-like state. Bel Peol tells Hecate to try and synchronise with the Reiji Maigo and she and Sydonay leave the room. Outside the room, Sydonay disapproves of Hecate synchronising with Yūji, where she is absorbing the Reiji Maigo's Power of Existence, with it overflowing from the Seireiden like a never-ending fountain. Sydonay is still worried about Hecate but notices Wilhelmina and Shana approaching Seireiden and watches them.

Sydonay sits with Bel Peol in a room, where they wonder how long Shana and Wilhelmina can last against a horde of Dominos without their Flame Haze powers. Later, Sydonay looks out the window at the fountain of existence, which is pouring out an excessive amount of existence. He sees Margery return and tells Bel Peol that he will greet her before leaving the room. He flies out of Seireiden in Manticore form, meeting Margery, who transforms into werewolf form.

Both Sydonay and Margery roar, able to use the Power of Existence from the fountain that is swirling around them as they face off. They shoot blasts of existence at each other, with flames rising all around them. Both Sydonay and Margery lose limbs, but are able to regenerate them. Marchosias asks Sydonay if he wants to fight and he replies that he is happy if Hecate is satisfied. He later hears Hecate's scream as she discharges all of the Power of Existence she absorbed from Yūji, fleeing from his fight with Margery to come to her aid. As Shana activates Tenpa Jōsai to save Misaki City from all the existence, Sydonay rescues Hecate from the flames of Alastor. He is able to calm her when she expresses that she is empty, before teleporting away.

Mare Arc
In a prayer room, Sydonay and Bel Peol sit while Hecate prays.

Sydonay and Bel Peol sit in a room in a temporary residence, which Bel Peol thinks is pathetic. Sydonay tells her that he's leaving to do his job, telling Bel Peol not to do anything strange to Hecate.

Milestone Arc
Note: This arc contains a flashback that depicts events occurring before the events of the main series.

Sydonay appears in New York in the 1930's, bursting out of a river in his Hydra form and whacking Margery, who was fighting Annaberg, with his tail. Margery attacks with balls of Power of Existence, but one of the heads sends her crashing against a building, knocking her unconscious. Sydonay transforms back into his normal form, with Annaberg appearing and thanking him for defeating Margery. Sydonay reveals that he is Annaberg's bodyguard and asks him if he should kill Margery, saying that this is the first time he had met her but he had heard of her killing his comrades. Annaberg declines the offer and disappears, with Sydonay walking away.

Margery chases Annaberg away from the Empire State Building, which causes him to fly away from her and use his fog to hide the presence of Sydonay, who is standing on the top of the building. Sydonay transforms into Manticore form and attacks Margery, who transforms into her werewolf form. She surrounds Sydonay with her clones, but he quickly realises that she is planning to use them to attack Annaberg. He then dives for Annaberg and covers his Manticore form with a rocky substance. While Annaberg is distracted with the rocky shell, Sydonay leaves it and attacks her from behind, giving her a severe wound. He then hears Yurī's voice through one of his butterflies, which he disposes of. Sydonay attacks Margery again, but is impaled and cut in half by Yurī's tornado. He falls, but recovers before regenerating. He is about to go after Yurī, but is attacked by Margery, who states that his opponent is her. They clash and bite each other before taking the fight to the ground. Sydonay claims that he is humiliated after Annaberg becomes his first client to die, after the latter was killed by Yurī. Both Sydonay and Margery begin to tire, with Sydonay thinking that the fighting is now pointless with no client. Yurī and his tornado approach, but Sydonay slashes him from behind. He then shoots him with his Power of Existence, with Margery doing the same on the other side (because she didn't want to risk her life to beat Sydonay, needing to kill The Silver), killing Yurī. This results in Sydonay and Margery's fight being a draw, and they both leave New York.

Sabrac Arc
Sydonay, wielding the Shintetsu Nyoi, leads an army of Denizens to the Dorel Party, an Outlaw Network based in Zurich, Switzerland and lead by Dorel Kubelík. Stolas moves forward from the army but Sydonay blocks him, choosing to attack by himself. He crushes the building with one swing with his transformed arm, which wielded the Shintetsu Nyoi. Sydonay looks on as the building burns, bidding farewell to Dorel, who died while inside the building.

Christmas Eve Arc
Sydonay returns to Seireiden, hanging around with Hecate at Dantalion's factory, where they see Bel Peol thanking Sabrac for battling the Flame Haze in Misaki City.

In the blue field that Hecate creates when she pulls the Reiji Maigo out of Yūji, Sydonay waits for the arrival of the Flame Haze. Margery enters the field in front of Wilhelmina and Shana, getting ambushed by Sydonay. He brushes away her attack and smashes her in the side with Shintetsu Nyoi using his mutated arm. As a bloody and unconscious Margery falls, Shana attacks Sydonay, but the latter is able to push her away. Dantalion explains to the Flame Haze their plan to activate the Statue of Pride before they rush at Sydonay. He shoots existence at them but they dodge, with Wilhelmina throwing a ribbon javelin at him. Sydonay destroys the javelin, allowing an opening for Shana to attack him, only to be blocked by Hecate. Sydonay still faces Wilhelmina, but watches as the Statue of Pride begins to awaken.

Sydonay and Hecate block the Flame Haze from Dantalion, with Sydonay again engaging in battle with Wilhelmina. He deflects her existence attacks, fires his own, and catches another javelin. He attacks Wilhelmina's ribbon shield with Shintetsu Nyoi, breaking it and sending her flying into the trashed Misaki City Clock Tower. He and Hecate approach Wilhelmina and Shana, with both of the Flame Haze injured and bloody. Sydonay is about to attack but stops, flying down to lure the Flame Haze away from the Clock Tower. The Flame Haze fly away and Sydonay follows. They return to the Clock Tower, where the Flame Haze realise that they don't want to damage the tower. They leave the tower again, with Sydonay following Shana before she returns to the tower, causing him to back off. Shana attacks Hecate, but is warded off by Sydonay. Both Shana and Wilhelmina attack them, but Sydonay grabs Hecate and evades, causing the attack to hit the Statue of Pride. Shana enters the hole they made and Wilhelmina then blocks it from Sydonay and Hecate. After the Statue of Pride breaks the blue field, Sydonay shoots a blast at Wilhelmina, who dodges. Wilhelmina is about to attack, but the Statue of Pride collapses after Yūji and Shana destroy its heart. Sydonay returns to Hecate, who doesn't know what happened. He tells Dantalion that it's time to go before teleporting away.

Arrival of the Snake of the Festival Arc
Sydonay attacks the Shanghai Outlaw, encountering Yu Xuan and her Crimson Lord Di Hong again. Yu Xuan reveals that Sydonay has killed the other members of the Shanghai Outlaw. She attacks Sydonay, who counters with the Shintetsu Nyoi. Yu Xuan uses her Shashin Kensei, exploding the area around Sydonay, but he appears behind her unscathed. He explains to Yu Xuan how the Shintetsu Nyoi can't break or bend unless he orders it to. He uses its ability to summon eyes on the building behind Yu Xuan, shooting out projectiles at her. She blocks them but drops her sword, which is Di Hong's Vessel, giving Sydonay the opportunity to destroy it. He then shoots out Power of Existence at Yu Xuan, killing her. Sydonay lands on a nearby building and is congratulated by Orobas and Lerajie. He tells them that Bal Masqué's new target is Sophie Sawallisch in Europe, describing it as not ideal.

Capture and Infiltration Arc
Sydonay returns to Seireiden and attends Bel Peol's war council. The two points of her plan is attacking enemy strongholds and intercepting enemies from multiple locations, which Sydonay thinks is dull and defensive. He points out that they have more numbers than the Flame Haze and could crush their plans, but Orobas feels that there will be no opposition after the destruction of the Shanghai Outlaw. After Decarabia angers Ribesal, Sydonay tells him to be mindful of others. Later, Sydonay meets up with Bel Peol at a spring and asks about their Leader, the Snake of the Festival. She tells him that their ambition hasn't met any obstacles and that Lamies will be arriving soon. She says that if Yūji interferes with their ambition, the Leader will stop him. Sydonay asks why the Leader didn't come to the war council and Bel Peol realises what he is implying and tells him that Hecate isn't with him. The two meet up with Fecor, with Sydonay commenting that their army is well prepared. Fecor uses Trivia to connect Bel Peol to Domino and Dantalion while Sydonay goes to Hecate, who is finalising coordinates. He tells her that he has done his jobs and asks Hecate if he can return to being the Leader's right-hand man, calling her "my cute Hecate". She disapproves of his remark, but welcomes him back as the "General" of Bal Masqué, making him laugh. Bel Peol arrives, telling Sydonay that he can be bold.

Sydonay appears in Shana's room at Seireiden after Yūji saves her from Hecate, smiling at the latter. Later, Sydonay drinks at the Seireiden bar with Stolas, the first time in a while that he has been there. He watches the Denizens, including Ribesal and Pirsoyn, who are to merry and frivolous. Sydonay stands and tells the Denizens that he will be leaving Seireiden on a mission. Purson, Stolas and Mammon tell him that it's okay and that they will protect the Trinity. Sydonay kicks Decarabia's Providence insignia on the ground, causing him to be summoned. He tells Decarabia to be cautious in the war and not let anyone die in vain. Decarabia tells him their plan; to enter a siege when the Flame Haze reach Seireiden, which Sydonay agrees with. Later, Sydonay attends Yūji's speech to countless Denizens, before entering the Divine Gate with Yūji, Hecate and Bel Peol.

Sydonay and the group stop on a large piece of ground, where they encounter the souls of the Flame Haze that sealed the Snake of the Festival in the Abyss. Sydonay helps the others escape, while he and Bel Peol stay to fight the Flame Haze. Sydonay offers to help Bel Peol but she says she doesn't need it, using her Tartaros to fight the souls. Sydonay also fights with Shintetsu Nyoi.

Into the Abyss Arc
Sabrac leaves the group to hold off the Flame Haze, while Sydonay and the others continue on towards the Snake of the Festival's true body, entering the temple that houses it. Sydonay wants to finish things quickly so that he can go back to help out in the war, but is criticised by Dantalion. They arrive at a gate and watch as it opens. They later stand on the God's body and watch as Hecate awakens it. The group rides on the Snake of the Festival's head as it slithers through the Abyss. Shana approaches them and Yūji tells Sydonay that she is his guest. He brings out Shintetsu Nyoi when Shana attacks Yūji, but is again warned by Yūji not to attack. Sydonay and the rest of the Trinity state that Shana is dangerous after she threatens the Snake of the Festival with Tenpa Jōsai if he gets rid of Yūji.

Sydonay and the group watch on as Yūji and Shana fight. After the Flame Haze defeat Sabrac, Sydonay is ready to fight them, but they escape the Abyss on bird Flame Haze souls. Sydonay, Bel Peol and Hecate meet up with Yūji on the head of the Snake of the Festival and they escape the Abyss.

Flame Haze Retreat Arc
Sydonay, Bel Peol and Hecate leave the Snake of the Festival and watch as Fecor dies. Sydonay and everyone else in the area listen to the Snake of the Festival's Declaration of the Grand Order; the creation of Xanadu.

Sydonay appears during a confrontation between the Flame Haze; Shana and Wilhelmina, and Haborym and his army of Denizens. He sees through the Flame Haze Army's plan, but challenges the two Flame Haze to try and stop him. He then tells Haborym to leave the fight to him and reform his troops. Sydonay tells the Flame Haze that he will kill them because he doesn't have any orders not to. The Flame Haze swoop in to attack him and he responds by leaping at them. He uses Shintetsu Nyoi to fight Shana, who retreats upwards. Shana charges at Sydonay, who transforms his hand into a Manticore head, but is sliced in half by Shana's Hien. He immediately clashes with Shana again, using another Manticore hand to neutralise Shana's flame punch, producing smoke. After the smoke clears, Sydonay had regenerated his body. Wilhelmina states that he should be prepared to die, warranting his transformation into Manticore form. He attacks the two while thinking that they aren't acting aggressively. He flies, annoyed when thinking that the Tendōkyū must have escaped when CenterHill appears in front of him and punches him in the gut. While Sydonay is distracted by CenterHill, Shana attacks him, but finds that the Flame Haze won't attack when he is in a certain area. He clashes with the three Flame Haze before concluding that they are hiding the Tendōkyū. Sydonay converts to Hydra form, making Shana use Shinku. She destroys all but one head, which transforms into Sydonay's base form. He rushes towards where he thinks the Tendōkyū is hidden, throwing an extended Shintetsu Nyoi at the spot, with CenterHill getting in the way. After ordering it to pierce through, it takes off CenterHill's arm, but was intercepted by Margery, who enters from an Unrestricted Spell. She traps Sydonay in another spell, but he is able to break out before getting attacked from behind by Chiara Toscana's arrow, allowing Margery, Shana and Wilhelmina to escape on it, leaving only CenterHill. He kills him and later meets up with Yūji and Bel Peol.

Preparations for the Final War Arc
As Dantalion reboots the Seireiden, Sydonay and the rest of the Trinity watch Yūji, who orders the Seireiden north-east to Misaki City.

As Kazumi and Yūji arrive on the roof of Misaki Municipal High School, Sydonay, along with Pirsoyn, Ribesal, Orobas, Lerajie, Bel Peol, Haborym, Mammon, and Stolas, line up around a carpet to greet her. The carpet leads to Seireiden.

Creation of Xanadu Arc
A black Fūzetsu is cast over Misaki City, and Sydonay and the other members of Bal Masqué watch Yūji and Kazumi ascend to Seireiden. In the throne room, Sydonay and Bel Peol appear over the Crystal Altar after Yūji summons Bel Peol. After Dantalion transforms the Seireiden into a tower-like shrine called Saishuku no Shadan, he asks the Snake of the Festival if he could get started with his preparations and is ordered to tell everyone to prepare for chaos. Sydonay agrees and leaves. He later returns to the throne room, taking off his glasses and comparing the events unfolding to that of three-thousand years ago. After Hecate announces that she will begin the third step of their ambition, she lifts herself up, blanking out the Crystal Altar, and creates silver, rippling ovals underneath Sydonay, Kazumi and herself. Sydonay says goodbye to her and she responds by saying that they will meet again before rising up towards the Snake of the Festival's body. After Hecate's silver oval falls to the ground, he explains to Kazumi that they are traces of Hecate's existence and that they are rippling because Hecate has been chosen for the Divine Summoning. He states that Hecate will be reborn and that her whole existence is heralding the Snake of the Festival's summoning. He watches Hecate begin the Taimei Shihen, visibly affected, and wonders when he'll see her next. When Shana and Wilhelmina enter the throne room, Sydonay transforms into Manticore form.

Shana and Wilhelmina rush towards Hecate and the Snake of the Festival's body, who are above, but are blocked by Yūji and Sydonay. Sydonay then watches as Yūji and Shana fight, saving Yūji when he was caught off guard by Shana's powerful attacks. He remarks that Yūji isn't good with women before dodging Shana's flames. Shana and Wilhelmina use this chance to fly towards the World Egg, with Sydonay using his flesh to throw Yūji after them. After Yūji blocks Shana's Chorde from hitting the egg, Sydonay meets up with him and returns to his base form. Wilhelmina wraps the two up in ribbons while Shana uses more Chorde rings, which are blocked by the egg's shell. The group watch as the Saishuku no Shadan begins to fall as a result of Khamsin Nbh'w trying to destroy it. Sydonay tells Bel Peol, who is inside the shrine, to take cover before throwing an enlarged Shintetsu Nyoi at it. It pierces the shrine at the top and drives through it, holding it up. Sydonay watches as Kazumi uses the Giralda to summon Pheles. Pheles informs the group that she will change the current situation before forming a twister. Sydonay stays at Saishuku no Shadan, watching as Khamsin joins up with the Hyakki Yakō and telepathically talks with Bel Peol about it, before asking Dantalion if he had fixed the shrine. Dantalion presses a button and the Saishuku no Shadan lights up, causing Sydonay to retract the Shintetsu Nyoi.

Sydonay throws the Shintetsu Nyoi from behind Yūji, almost hitting Shana, who was saved by Wilhelmina, who had just arrived with Margery. Sydonay meets up with Yūji, who thanks him for coming. Sydonay tells him that Shana is a big threat and that Bel Peol thinks that Khamsin had set something up inside the Saishuku no Shadan. He transforms into Hydra form, shooting his Power of Existence at Margery, who counters with her own. Wilhelmina blocks his attack and is able to restrain one of his heads. Another of Sydonay's heads attacks Shana, who defends with a flame attack. Sydonay returns to his base form before being trapped by Wilhelmina, the ribbon also attached to Margery. Margery, who is still in Werewolf form, punches him, causing the ribbon to drop. As Sydonay falls, he thinks that the Flame Haze are trying to separate him from the Leader. Margery attacks Yūji, but Sydonay saves him by transforming his limbs into four separate Manticores, with one taking Margery's blast, one taking Yūji away, one chasing Shana and one attacking Wilhelmina. Wilhelmina wraps up the Manticores near herself, Shana and Margery, while the latter blocks the last Manticore and Yūji with an Unrestricted Spell. The Manticore hits it and is vaporised, with Yūji falling to the ground. Sydonay sees Yūji fall, but it again restrained by Wilhelmina, with Margery coming up from behind him. He watches as Yūji uses his own Unrestricted Spell, to stop Shana's flames. He also watches Shana break through the spell and hitting the World Egg with Chorde rings.

Sydonay, in Manticore form, watches the Chorde rings hit the World Egg. He rushes over to see if Hecate is alright, but she lets him know that she is unhurt but sick. Sydonay then returns to Yūji, where Shana tells them of the new rule she added to Xanadu; humans shall not be eaten. Yūji tells Sydonay to not hold back in the coming battle.

Sydonay and the group watch as the Hyakki Yakō's van, along with Khamsin and Kazumi, gets blown up by cannon Rinne. He wonders why the Engaged Link won't assist Khamsin and the others, dodging Margery's blasts and attacking Margery and Shana, who were saved by Wilhelmina. He blocks himself and Yūji from Margery's blasts, attacking when Wilhelmina leaves to help Kazumi's group. Margery then rushes at Sydonay before they reach a standstill. He again returns to Yūji, watching as Bel Peol finishes the final preparations for the Taimei Shihen by activating the Conloquium. Hecate moans that she is still sick, causing Sydonay to figure out the Flame Haze's plan; to tamper with the Conloquium, Bal Masqué's backup system for the Taimei Shihen.

Yūji claims to the group that the Conloquium was a decoy, with the Reiji Maigo modified by Dantalion to absorb all of the distortions caused by Denizens the real plan. Sydonay watches as the Snake of the Festival undergoes Saiki Reisō and looks up at Hecate before sensing Rofocale performing Shōhi Ginsei. Shaher tells everyone in the area about the Heir to Both Worlds. Later, Sydonay watches on with a hint of sadness as Hecate is sacrificed to create Xanadu from the wishes of the Denizens. He meets up with the Snake of the Festival and Bel Peol at the Seireiden shrine, Saishuku no Shadan. Sydonay allows Bel Peol to summon the troops, as there won't be any more fighting. After Bel Peol summons Ribesal, Sydonay notices that he is reluctant to follow the Snake of the Festival's order to enter Xanadu without Pirsoyn, his Jaeger companion. After most of Bal Masqué leave for Xanadu, Sydonay tells Yūji and Bel Peol that he will stay with the former because he made the Leader enjoy himself while fulfilling his ambition. The God of Creation allows this and Sydonay and Yūji watch as he leaves with Bel Peol for Xanadu.

Sydonay and Yūji watch the path to Xanadu when Lamies approaches them. He tells them that he has collected enough Power of Existence and restores his painting, something that was lost to the world. Lamies leaves after altering Azure's spell and giving Yūji's Unrestricted Spell a name, revealing his true form as Leanan-sidhe. Sydonay and Yūji then wait for the Flame Haze on top of Misaki Bridge, where Shana, Margery and Kazumi fly up to meet them. Yūji reveals to the group his plan to restore all the people that were devoured in Misaki City using Lamies' spell and the Power of Existence left behind by Denizens. After Yūji retrieves Kazumi, he orders Sydonay to attack, which he does by transforming into his Powered Exoskeleton form, carrying Yūji on his neck. Margery transforms into a multiple-headed werewolf and she begins battling with Sydonay after the Fūzetsu around the city disappears. He charges at her and connects with a kick, but gets bitten as the two take the fight to the sky. He rips off one of her heads but Shana is able to slash off one of his arms with her flames. Sydonay protects Yūji from more of her flames. Margery bites Sydonay and he bites one of her heads off her neck as Yūji and Shana ascend to have their own fight. Sydonay is again engulfed in Shana's flames, allowing Margery to ensnare him in her strongest Improvisational Poem of Slaughter. Sydonay is killed by Margery's poem, which was the simultaneous blasts from her heads which were equivalent to the power of over ten thousand Flame Haze's flames (ten million in the anime). Sydonay then appears in a dreamlike afterlife with Hecate, who was surprised he had been killed. He tells her he feels that he wanted to die. They hold hands and walk towards a white light, hoping for the day the Trinity and their leader are together once more.

Shakugan no Shana-tan
In the third episode, Sydonay is at Seireiden and watches Hecate pray. He later stands against a pillar with Hecate-tan on top of his head. He comments that he can't see her "cute" face. She tells him to shut up, which he also finds cute, inhaling deeply for no apparent reason. In a parody of Shakugan no Shana Episode 13, Sydonay has Yūji pinned to the bridge, where he reaches inside him for his Treasure Tool. He looks embarrassed when he figures out what it is and tells Yūji that he will take away what's "precious" to him. As Yūji moans, Sydonay asks him if he can still "hold it in", dismissing his protests that Shana is watching. Shana-tan and Hecate-tan are on Yūji and Sydonay's heads respectively, with Hecate-tan calling both of them perverts. Back at Seireiden, Sydonay calls Hecate-tan cute again. She tells Bel Peol, who is also in the room, that the place smells like an old man, making Sydonay crumple to the floor. Bel Peol teases him by saying he is conscientious of it. Later, in Misaki City, Sydonay dawdles after Hecate-tan, who is with Shana-tan on Yūji's head, whispering her name.

In the ninth episode, Sydonay features in Fumina's memories. In her memories, Sydonay is a sports teacher who tries to keep her under control, but she makes him cry. She later approaches him and joins his school rugby union team, with the goal of nation-wide domination.

In the fifteenth episode, there is a parody of Shakugan no Shana Final Episode 18, where Hecate-tan is on Sydonay's head and is preparing to be the sacrifice for the Divine Summoning at the Saishuku no Shadan. Sydonay is again inhaling deeply at Hecate-tan's cuteness and begins to say goodbye, but Hecate-tan doesn't want to go. She says she doesn't know when they will next see each other if she becomes the sacrifice, but he can't hear her. After she is scolded by Bel Peol, Hecate-tan says farewell to Sydonay and disappears. He yells at Bel Peol, before being kicked. Later, Sydonay attends Bel Peol's Naze Nani Shana-tan class. He and the others ridicule François about the form of Grogach's Vessel.

Bel Peol
Sydonay is usually on good terms with Bel Peol, but won't forgive her if she does any harm to Hecate. When referring to her, he calls her Babā (ババア), which is roughly translated into "old hag".

Hecate
Sydonay tends to care a lot about Hecate, often calling her "My Hecate" (俺のヘカテー), which she dislikes. He states that he likes how she is "pure", not wanting anything to contaminate this purity. He knows about Hecate's purpose for existing, but was still visibly affected when Hecate began the Taimei Shihen, with Kazumi noticing. He was also sad when Hecate sacrificed herself to create Xanadu.

Natural Abilities
Power of Existence Manipulation: Sydonay is able to enter the existence of Torches, reaching inside Yūji in order to find out which Treasure Tool he possesses.

Flight: Even without transforming, Sydonay is able to fly at various speeds.

Fire Resilience: Sydonay is impervious to flames to some extent, being able to leap through Alastor's flames in order to rescue Hecate.

Teleportation: Sydonay is able to vanish or teleport away from his current location, disappearing after being enveloped by his flame.

Master Tactician: During his second confrontation with Margery in New York, when Margery was using her Improvisational Poem of Slaughter, Sydonay was able to determine that she was going to attack Annaberg.

Enhanced Reflexes: Sydonay was able to catch a ribbon javelin hurled by Wilhelmina with his bare hands.

Regeneration: Even while in his base form, Sydonay is still able to regenerate parts of his body that he has lost during battle.

Enhanced Strength: To Margery's surprise, Sydonay was able to break free of her binding spell faster than she expected.

Telepathy: Sydonay was able to converse with both Bel Peol and Dantalion, who were far away from him. He was able to hear what they were saying and vice-versa.

Unrestricted Spells
Tatsui no Gen (達意の言): Sydonay is able to use Tatsui no Gen to understand words that are foreign to him. When Tiriel talks about Orgel, Sydonay was able to equate the word to "music box".

Endan (炎弾): Sydonay is capable of creating a spark or ray of existence from his hands, which he demonstrates with his index finger. Sydonay used this spark to destroy one of Yurī's butterflies, so it is likely that he can produce a much stronger blast. Later, while using Shintetsu Nyoi, Sydonay released a tornado or ball of Power of Existence at opponents, which was notably stronger than the spark.

Treasure Tools
Shintetsu Nyoi (神鉄如意): Sydonay often wields his Treasure Tool, Shintetsu Nyoi, into battle. It is the shape of a polearm and can't break or bend unless Sydonay orders it to. He also often wields it while using his mutated arm, causing severe damage to opponents. Sydonay has proven to be quite capable of fighting with the polearm, having the advantage during battles with Wilhelmina. Additionally, it has the ability to shoot out projectiles from a nearby surface, with the projectiles coming out from shapes that resemble eyes and mouths. Sydonay can make the polearm materialise and dematerialise at his will, as well as increasing its size.

Transformation
Sydonay has the innate ability to transform to a variety of chimera-like creatures, most of them having wings and a lion's head. Whether this is an Unrestricted Spell or simply the ability of Crimson Denizens to change their appearance is unknown.

Manticore Form: Sydonay's most used transformation during combat, which gives him the appearance of a Manticore. He becomes much larger, with the body of a lion, the hands and feet of a bird, the wings of a bat, a green lizard's tail, and a long horn on his head.
 * Telepathy: While in Manticore form, Sydonay can still talk to people, but doesn't have to open his mouth because he still has his normal conscience.
 * Flight: Sydonay is able to fly and levitate because of his wings. Additionally, he is able to fly when he was cut in half by Yurī Chvojka's tornado, propelling himself by gushing out his Power of Existence from the wound he received.
 * Enhanced Strength: Sydonay is able to effortlessly hurl Margery into the side of a building with one hand, using great force.
 * Power of Existence Manipulation: Sydonay is able to release a ball of Power of Existence from his mouth, which has enough power to reduce a building to rubble. He can also form and release balls from his hands.
 * Body Alteration: While in Manticore form, Sydonay can reveal part of his usual, human body. He was able to alter his flesh to throw Yūji up after Shana and Wilhelmina when they were flying to the World Egg.
 * Regeneration: Sydonay is able to regenerate limbs that he has lost during battle.
 * Rock Manticore Form: Additionally, Sydonay can coat his Manticore form in a durable, rock-like substance, which covers him like a shell as he forms a ball. Only his face, wings, and lizard's tail are left uncovered. He later covers these parts when he protects Annaberg. He can also detach the rocky shell from his body, leaving it to fool opponents.


 * Flight: Sydonay can still fly, or at list maneuver his decent because his bat wings are left uncovered by the rock.
 * Immense Durability: Sydonay is extremely resilient, able to withstand an attack from Margery's Improvisational Poem of Slaughter, which caused severe damage to the Empire State Building.
 * Manticore Variant Forms: Sydonay can transform his hand into the head of a Manticore and can attack using this head. This has proven to be quite strong, being able to neutralise Shana's flames. He can also transform his limbs into four separate Manticores.

Serpent Form: Sydonay uses this form to quickly escape during the conflict between the Aizen Siblings and Shana. He takes on the appearance of a long purple serpent and is best suited for quick escapes while underwater. Sydonay can most likely breathe in water while using this form.
 * Enhanced Speed: Sydonay was able to dart away at an exceptional speed from Margery during their first fight in Misaki City while underwater.

Hydra Form: Sydonay uses this form mostly during battles which take place underwater, often starting conflicts by attacking first from beneath the surface of the water. This form resembles the mythical Lernaean Hydra. With this form, Sydonay has the advantage of having multiple heads, which can all attack simultaneously. During his attack on Margery in New York in the 1930's, the Hydra form had four heads, while during the final battle to create Xanadu, he only had three heads.
 * Enhanced Strength: While in this form, Sydonay was able send Margery crashing into a building and knocked her out by bumping her with one of his heads.
 * Enhanced Speed: When Sydonay figures out the location of the Tendōkyū, he rushes at it with great speed using his Hydra form.
 * Power of Existence Manipulation: Sydonay is able to release multiple balls of Power of Existence from his mouth at a rapid rate.

Mutated Arm Form: Sydonay is able to transform his right arm, so that is becomes significantly longer, about twice as long as his body. It is covered in blue fur and spikes. He uses this ability while in combat with his Shintetsu Nyoi, which he wields with his mutated arm.
 * Enhanced Strength: Sydonay was able to destroy the entire Dorel Party Outlaw building with one swing of the Shintetsu Nyoi when his arm was mutated. He was also able to cause severe damage to Margery by smashing her in the side with Shintetsu Nyoi using the arm. He is strong enough to remain untroubled when Shana attacks, easily pushing her back.
 * Enhanced Durability: With his mutated arm, Sydonay was able to brush away Margery's Power of Existence attack with ease, causing no damage to himself at all.

Powered Exoskeleton Form: This form is by far the largest of Sydonay's transformations. He becomes a large, armored humanoid being. He wields the Shintetsu Nyoi, which is also enlarged.
 * Flight: Sydonay was able to engage in battle with Margery in the air.
 * Enhanced Strength: During their fight in Mana River, Sydonay is able to push a multiple-headed werewolf form Margery around, with Margery weighing enough to flood Misaki City if she falls down. He is also capable of ripping off one of Margery's heads with one arm.
 * Immense Durability: Sydonay is initially able to withstand Margery's strongest Improvisational Poem of Slaughter, which, according to Marchosias, was equivalent to the power of ten thousand Flame Haze combined.

Quotes

 * (To Margery when facing off with her on the bridge): "I'm delighted that you showed up on your own, beautiful assassin."
 * (To Margery after snatching her in mid-air): "My condolences, Chanter of Elegies. Look at how weak you are. I'm very disappointed."
 * (To Margery after blasting her): "I hope you have a good time in hell, Margery Daw."
 * (To Bel Peol about Hecate): "That innocence is what makes my Hecate nice. I hope there's no harm to Hecate in this plan."
 * (To Hecate): "Hecate, you really are pure; please remain that way."
 * (To Marchosias): "I am happy if my Hecate is satisfied."
 * (To Margery and Marchosias when attacking them in Manticore form): "Beauty isn't supposed to be hidden, is it?"
 * (To Margery after severely injuring her): "I wonder how the withered flower will enchant my eyes."
 * (To Shana when she attacks Hecate): "Stay off of my Hecate."
 * (To Yu Xuan about her Shashin Kensei): "Quite a beautiful skill. But it's not enough to claim my heart or my life."
 * (To himself after killing Yu Xuan): "The death of a young beautiful girl grips the heart like a withered flower."
 * (To Wilhelmina and Shana during the Second Great War): "I'm sure you've achieved your objective by now. This time, try stopping me. Besides, I've always wanted to really cut loose against you guys."
 * (To Wilhelmina and Shana): "Our Leader hasn't ordered us not to kill you guys. Therefore... I'll kill you."
 * (To Hecate when she begins the third step of Bal Masqué's ambition): "See you, my cute Master Throne, Hecate."
 * (To Yūji after saving him from Shana): "I didn't think the Leader, who's lived as a human, would be this bad with women."

Trivia

 * Sydonay's name is derived from the biblical demon Asmodeus, who is depicted in Collin de Plancy's Dictionnaire Infernal with the features of a chimera-like creature. "Sydonai" or "Sidonay" are among the alternate spellings for Asmodeus.
 * Sydonay often fights with Margery Daw ever since they met in New York in the 1930's.
 * Sydonay is highly favored by the Snake of the Festival as "he who brings an end to anything that stands in God's way".
 * Being a kin of the God of Creation, after being killed by Margery Daw and Shana, he returns to slumber with the other kin, the sacrificed Hecate, until they are needed again when the Crimson Denizens wish to the Snake of the Festival.