Evolt

"I'm the game maker. I derive the best strategy by considering every possibility. Everything is going as planned."

- Blood Stalk's speech to Night Rogue. "Even if I had never come to Earth, you people would've found yourselves causing another war soon enough. I remember telling you this before. Science always ends up causing destruction! Scientific advancement makes life more convenient, and people start to take things for granted. Before they know it, they will find themselves embroiled in war. That's the future...that science promises!"

- Evol's speech to Build in episode 35.

Blood Stalk is one of the leaders of the organization Faust and the primary antagonist of Kamen Rider Build. He initially appears as a subordinate of Night Rogue, though is eventually revealed to be manipulating both the villains and the heroes towards his own goal of constructing the Pandora Tower and using it to wipe out all life on Earth.

His true identity is Evolt, a mysterious entity who annihilated the ancient civilization on Mars long ago using the power of the Pandora Box. He took over the body of Soichi Isurugi, owner of the cafe nascita and secretly the astronaut who discovered the Pandora Box 10 years ago, and used him to trigger the Skywall Disaster that separated Japan.

Later on in the series, Evolt obtains back the Evol Driver, granting him the power to transform into Kamen Rider Evol.

Blood Stalk/Evolt is voiced by Tetsuo Kanao.

Past
In the ancient past, Evolt used Pandora Box to create the Pandora Tower and annihilate the civilization of Mars with a massive distortion. To prevent him from moving on to other planets, Vernage, the Queen of Mars, fragmented Evolt's spirit from his body and sealed his power away in the Pandora Box.

Following the destruction of Mars, a fragment of Evolt's essence traveled to Earth with a Martian probe. After the probe was discovered, Evolt's essence entered the body of a security guard for the probe, Yuri Banjou and fused with her unborn son Ryuga. Ryuga was born a month later, containing the essence inside him though it did not influence his personality.

Ten years prior to the events of Build, Soichi Isurugi, an astronaut working with the Kiwami Project, discovered the Pandora Box while on Mars. Soichi unwittingly released Evolt's consciousness and possessed by him. At the ceremony back on Earth, under Evolt's control, Isurugi applied his hand to the Pandora Box, causing the Sky Wall Disaster.

"Soichi" was later arrested and placed in a mental hospital, along with his daughter, Misora Isurugi who was also exposed to the box and gained the ability to purify Fullbottles.

However, "Soichi" escaped about a month later and went to Shinobu Katsuragi to get him to invent the Lost Bottles and the Rider System. Searching for ideas for the 60 empty Fullbottles he had, Evolt probed Soichi's mind for the 30 Organic Fullbottles, with Soichi offering up things Misora liked such as animals. Evolt then asked Soichi for things that could destroy those 30 things to use for the 30 Inorganic Fullbottles, to which Soichi initially offered up tanks and other weapons, but later switched random things likes comics to avoid bringing harm to the things that Misora liked.

Seven years later, he was appointed as a special consultant for the Pandora Box. He also co-founded Faust with Gentoku Himuro and Takumi Katsuragi.

Under Faust
Misora later joined Faust to purify the Fullbottles for them, though she was unware at first of their true purposes. When she eventually found out about Faust's intentions, she lost her will to continue working for them. "Soichi" then "saved" her and took her back to the cafe, where he convinced her to continue purifying the bottles for good.

"Soichi" later stole the Pandora Box panels from the Touto Institute of Advanced Matter Physics to ensure their confidence and plastered into one of nascita's basement walls. He also took along a Build Driver and some Fullbottles from Faust.

Dealing with Katsuragi
When Takumi Katsuragi attempted to quit Faust, Blood Stalk knocked him out and switched his clothes and face with Taro Satou, whom Stalk had previously killed by Stalk. Stalk then left Taro Satou in the alleyway and erased Takumi's memories before talking him back to Faust to experiment on him. On September 5th, Isurugi brought the amnesiac Katsuragi to a small alleyway. After Takumi woke up, Soichi renamed him Sento Kiryu and nurtured him into Kamen Rider Build so that, with Build fighting more monsters, Soichi would have reasons to have Misora purify more bottles.

Encounters with Build
Blood Stalk was first seen by Build when he showed up to take Masahiro Nabeshima after he was reverted from his form as the Mirage Smash by Build. He injected Sento in the back with poison that left him stunned and unable to do anything while Stalk retrieved the unconscious Nabeshima.

Later, Stalk showed up again as Build was fighting the Square Smash. Stalk stood up from the park bench he was sitting on and fired a Devil Steam from his Steam Rifle at the Square Smash, causing it to grow giant. After observing Build fight and defeat the Smash, Stalk leaves and returns to Faust's lair. Night Rogue questions Stalk as to why he didn't kill Build, but Blood Stalk assures him that Build being left alive is all according to plan.

After discovering out Ryuga took Misora sightseeing outside nascita, Blood Stalk had Faust Guardians sent to their current location. He showed up as Ryuga was facing Night Rogue and Misora was passed out and told Rogue to not act behind his back. When Ryuga tried to flee with an unconscious Misora and fled, Night Rogue attempted to pursue him but was stopped by Stalk stopped him. Returning to Faust's lair, Stalk demanded Night Rogue to know why Rogue plotted behind his back. Rogue then informed Stalk that Faust's benefactor, Juzaburo Namba, president of Namba Heavy Industries Ltd. had asked to be given the Rider System and threatened to ally himself with either Hokuto or Seito if he did not receive it. As Rogue cancelled his transformation, Stalk asked Gentoku what he intended to do. Gentoku ultimately decided that they should steal the Pandora Box from the Touto Institute of Advanced Matter Physics in order to cause the three regions to declare war on each other.

Theft of the Pandora Box
The next day, Stalk and a squad of Faust Guardians waited in the garage level of the Touto Institute of Advanced Matter Physics. While Shingo Kuwata distracted Build, Eita Kawai disabled the security lock at the garage level, allowing Stalk and his Guardians to enter the Institute. Proceeding to the entrance floor, Stalk killed the four security officers stationed there by injecting them with a poison that disintegrated them. He then had Kawai trap the three Prime Ministers, Nariaki Utsumi, two security officers and the Pandora Box in an energy dome until he reached the floor where the box was located. Pursued by Touto Guardians and Touto Special forces, Stalk converted the Touto Guardians into Faust Guardians and went on his way. As he reached the eleventh floor, the dome dispersed, allowing Stalk to proceed toward the Pandora Box. He killed the two security officers with his poison before telling the Prime Minsters that he'll be taking the Pandora Box. Prime Minister Yoshiko Tajimi of Hokuto attempted to defy Stalk, but Stalk caused her to back down by threatening her with his Transteam Gun before using it to destroy the security cameras.

Making his way to the roof with the Pandora Box, Stalk was approached from behind by Ryuga, disguised as a Touto Security officer. Praising Ryuga for his boldness, Stalk had his Faust Guardians engaged Ryuga, but Ryuga defeated all of them with the power of his Dragon Fullbottle. Intrigued by Ryuga's power, Stalk attempted to fight him until Kawai showed up and told Stalk to leave Ryuga to him. Obliging, his request, Stalk used his Steam Blade to infuse Kawai with Devil Steam and turn him into a Press Smash Hazard and leaving Ryuga to fight the Smash. On the rooftop, Stalk was confronted by Gentoku, who told Stalk the roof wasn't in their escape route. Stalk told him he was lost, Gentoku was unconvinced and commented on how Stalk had shot out the security cameras to cover his tracks. Transforming into Night Rogue, he demanded Stalk hand over the box, but Stalk refused. Rogue then engaged Stalk until Ryuga showed up and interrupted their fight. Stalk asked him what had happened to the Smash, to which Ryuga informed him that he beat it but couldn't extract the Smash element without an empty Bottle, surprising Rogue and impressing Stalk.

Ryuga then attacked Stalk, but was swiftly defeated due to the injuries he sustained from his previous fight with the Press Smash Hazard. Build HawkGatling then arrives to help him, prompting Rogue to assist Stalk against them. While Rogue fought Build, Stalk battled Ryuga. Stalk soon discovered that Ryuga's Hazard Level has risen to 3.0, and commended him for finally awakening his full power, though it still wasn't enough to beat him. As Stalk overpowered Ryuga, Build FireHedgehog ceased fighting Rogue and attacked Stalk. Rogue then used the opportunity to sneak-attack Build, giving Stalk the chance to insert his Cobra Fullbottle into his Steam Rifle and fire a Steam Shot at both Rogue and Build, knocking Rogue to a wall and cancelling Build's transformation as well as causing him to drop the majority of his Fullbottle collection. Stalk takes the Pandora Box and leaves.

Returning to the ground floor, Stalk finds the Press Smash Hazard and defeats it and extracts the Smash element from it, reverting it back to Kawai. As Stalk left, Kawai questioned Stalk if he was Takumi Katsuragi, suggesting that the Devil's Scientist had faked his death, but Stalk denies his claims. Kawai refused to believe him and stated that Katsuragi could've used modern technology to transfigure a corpse. Stalk then approached Kawai and demonstrated his ability to do so, painfully molding Kawai's face into Kuwata's. As Sento rushed to an unconscious Kawai, Stalk fused with a Faust Guardian Union State and fled. Pursued by Build RabbitTank, Stalk shot at Build to get him off his trail. However, Build managed to destroy one of the Union State's legs before finishing it off with the Machine Builder's axle saw, forcing Stalk out of the Union State.

Having overheard Stalk's conversation with Kawai, Sento questioned Stalk as to why he faked his death, framed Ryuga and injected Sento with the Nebula gas, but Stalk asked Sento if that's what he should really be asking. Sento then asked him why he created Faust, the Smash, and if the Rider System was a tool to protect the innocent. Stalk replied by knocking Sento down and telling him the Rider System was a military weapon for bloodshed, telling him science leads to destruction. Refusing to believe Stalk's claims, Sento states that if used properly, science can bring people happiness. Night Rogue then appears and knocks Sento out from behind. Having his Faust Guardians circle them and point their rifles at Stalk, Rogue questions Stalk about where he intended to take the Pandora Box. Stalk tells him that he was going to take it to their lair, offering Rogue the box. Taking the box, Rogue grabs Stalk to threaten him to not try a stunt like that again, before stealing the Rabbit, Tank and Lion bottle from an unconscious Sento. As Sento returned to consciousness, he grabbed Rogue's leg, demanded he return his bottles, but Rogue just kicks him in the face before walking away laughing.

Betrayal of Night Rogue
After Gentoku refused to reveal the location of the Pandora Box due to Stalk's treachery, Stalk began searching for the box on his own, eventually tracking it to the Namba Heavy Industries Integrated Science Laboratory. Stalk skirmished with both Sento and Ryuga and Night Rogue before teleporting away with the Box.

After Gentoku disbanded Faust to cover his tracks, he discovered that Juzaburo Namba had dropped Gentoku as a partner and instead partnered up with Blood Stalk.

His true identity was eventually discovered by Build and Ryuga after they defeated him in a fight and cancelled his transformation. His cover blown, Isurugi revealed to the two that Gentoku was Night Rogue and allowed them to keep the Green Panels and the Pandora Box.

Rebuilding Faust
Blood Stalk later rebuilt Faust within Hokuto and temporarily aligned with them, providing them with the resources they needed to engineer Smash and the schematics for the Sclash Driver, allowing them to to create Kamen Riders. With former farm owner Kazumi Sawatari as their test subject, Blood Stalk and Faust used him to create Kamen Rider Build. They also developed a new form of Smash called Hard Smash, who were capable of retaining their consciousness in their Smash transformation. Stalk and Faust turned three farm workers of Kazumi's into Hard Smash, and they would come to be known as the Hokuto Three Crows.

Working with Namba
Stalk later switched over to working with Seito when they invaded and conquered Hokuto with backing from Namba Heavy Industries Ltd. He converted a now banished Gentoku Himuro into Kamen Rider Rogue so he could be used as the Kamen Rider of Seito.

After Seito lost a proxy battle with Touto and thus had to relinquish the Fullbottles and Pandora Box as per their agreement, Blood Stalk was summoned by Namba to kill Seito's Prime Minister Masakuni Mido and swap their faces so Namba could take control of Seito.

Becoming Evol
Stalk later attempted to get Sento and Ryuga to hand over the Evol Driver so he could regain his long lost power. The two were ready to deliver the Driver to Stalk, but chose not to and fought off Stalk with assistance from Kamen Rider Rogue. After being soundly defeated by the Riders, Stalk attempted to retreat but was chased down and knocked out of his transformation by Rogue. However, thanks to the actions of Nariaki Utsumi, Evolt managed to gain the Evol Driver and transform into Kamen Rider Evol. Overpowering Rogue, Evol prepared to finish Gentoku off but his attack was blocked by Gentoku's father Taizan.

Completing the Pandora Box
"The time is finally here. Taste the despair!"

- Evol as he constructs the Pandora Tower.

Eventually, Evol possesses Ryuga and obtains all of the panels of the Pandora Box and uses them to assemble it and use it to create the Pandora Tower to destroy Earth. Horrified, Juzaburo Namba sends Nariaki Utsumi out to go stop him, but Evol simply shoots him away with the Nebulasteam Gun. He then laughs as the Pandora Tower is completed, declaring that "Earth is finished".

Evol then uses the Pandora Box to create the Evol Trigger, the device that allowed him to destroy Mars, but discovers that the body of Ryuga is not strong enough to use it. He is then ambushed by Vernage possessing Misora, who knocks him against a wall before teleporting away with Sento and the Pandora Box. She then explains to Sento, Kazumi and Gentoku who Evolt is and how he annihilated all life on Mars.

Back at Seito's capital, Evol claims to Namba and Utsumi that he created the Pandora Tower to showcase Namba's power to the world. Though unnerved, Namba goes along with Evol's explanation. Evol is later seen in Ryuga's body leading a Seito on Touto before Build steps in to fight him. Transforming into Evol Dragon, Evol and Build fight, and Evol reveals to Build that the whole point of Project Build was to create someone strong enough to harness the energy of the Evol Trigger. Discovering that Build has raised his power to superhuman levels, Evol abandons Ryuga as a host and tries to possess Sento, but Sento reveals this was his plan all along and attempts to kill both Evol and himself by rapidly raising his Hazard Level until he overclocks. However, Sento's plan fails and Evol succeeds in claiming Sento as a host, much to Ryuga's horror when he wakes up.

Possessing Sento
Ryuga attempts to transform into Kamen Rider Cross-Z to fight Evol Rabbit, but Evol reveals that he removed all of his alien DNA from Ryuga's body when he exited it and that without it, he cannot transform into a Kamen Rider. Kamen Rider Grease then tries to attack Evol, but Evol effortlessly beats him down and cancels his transformation before leaving. Meeting with Namba, Evol reveals his true origins to the war profiteer, but claims he only wants to regain his former power.

Evolt later arranges a meeting with Ryuga Banjou and Kazumi Sawatari, promising to return Sento to them if they hand over the Pandora Box. At the meeting spot, Evolt notices that he is being accompanied by Engine Bro's and Remocon Bro's, who were sent by Namba to keep an eye on him. After Ryuga and Kazumi arrive, Evolt reveals that he has no intention of letting Sento go, as revenge for him impeding the progress of his plans. He leaves the two to be fought by the two Kaisers, not considering them worthy of being taken care of by himself, though he does interfere in the battle when Grease starts to gain the upper hand.

However, after Kamen Rider Rogue appears and defeats Remocon Bro's and Engine Bro's, Evolt decides to enter the battle himself. Transforming into Evol Cobra, Evol engages Rogue and manages to overpower him after switching to Evol Rabbit. During the battle, unknown to Evol, Ryuga managed to snatch the Dragon Fullbottle off of Evol's belt. He then attacks Evol untransformed and somehow manages to inflict damage upon him. Shocked, Evol questions how he is able to do that without his DNA inside of him. Ryuga then uses the Dragon Fullbottle to transform into Cross-Z and then Cross-Z Magma before engaging Evol alongside Kamen Riders Grease and Rogue. The three combine their energies for a final attack against the Kamen Rider, but Evol manages to absorb their energies and use them to transform into his final form, Evol Black Hole, setting Sento free in the process.

Black Hole
"Phase 4... complete!"

- Evolt after assuming his Black Hole form.

Assuming his true form, Evol congratulates the Kamen Riders on helping him re-achieve his true powers, declaring that nothing can stop him now. The three Kamen Riders then attack Evol, but he manages to effortlessly fight them all off, forcing them to retreat back to nascita.

Taking the form of Soichi Isurugi, Evolt approaches Namba and declares his intent to supplant Namba Heavy Industries as the country's ruler, though offers to let him keep his spot as Prime Minister. Namba refuses, but Evolt decides to give him a day to think it over. He later approaches Nariaki Utsumi and proposes that he come work for him, complimenting his skills as a scientist. He then reveals to Utsumi a second Evol Driver.

The next day, Evolt is approached by Nariaki Utsumi, Remocon and Engine Bro's and a squad of Hard Guardians. Utsumi pulls out a tablet and from it, Namba declares his refusal to go along with Evolt's plans. Unfazed, Evolt assumes his form as Black Hole and teleports everyone present to a barren battlefield for them to fight at. The Hard Guardians all charge at Evol, but the alien destroys them all at once with only a fraction of his power. The Washio brothers then try attacking Evol, but they fair little better and are easily beaten down. However, backup soon arrives in the form of Kamen Riders Build, Cross-Z, Grease and Rogue, who all attempt to take on Evol again. Despite the best efforts of the Riders and Kaisers, Evol proves too powerful for them and eventually announces his intention to finish things, using his Black Hole finisher to kill Rai Washio.

Using his brother's Fullbottle to assume Hell Bro's, Fu Washio charges at Evol in a fierce attack to take him down, which fails. Before he can be killed however he is saved by Cross-Z Magma, who attempts to fight off Evol to little success. Forcing Ryuga out of his transformation, Evol prepares to finish him off, but Ryuga is pushed out of the way at the last second by Hell Bro's, who absorbs the attack instead. Forced out of his transformation by the attack, Fu Washio also dies, but not before proclaiming how nice it was to fight for someone else's sake.

Evol then opens a portal to Juzaburo Namba's office and goes to kill him. Namba pleads for Evol to spare his life, offering up his company to him if he lets him live. Amused by Namba's cowardice, Evol declares that he loves how disgusting humans are and gives Namba a hug, only for him to kill Namba right afterword by causing him to disintegrate.

Evol then returns to the battlefield and restates his offer to Nariaki Utsumi, tossing him Namba's cane. Believing that since Namba is dead now nothing matters, Utsumi accepts Evol's offer, causing Evol to laugh and declare that he doesn't even want to destroy Earth anymore. Evol tosses Utsumi the second Evol Driver and Utsumi uses it to transform into a Kamen Rider, with Evol declaring him to be "Kamen Rider Mad Rogue".

Final Plan
Back at the Pandora Tower, Evol informs Nariaki that he will be assuming the identity of Masakuni Mido now that Namba's dead and that they will be seizing control of Touto and reuniting Japan, stating that it will make things easier in the long run. Utsumi then asks Evol what he intends to do about the Kamen Riders, to which Evol replies that he intends to still keep on using them to further his goals, instructing Utsumi to bring them to him alive. Admiring his Evol Driver, Utsumi inquires to Evol where the second one came from, as he had previously believed their to only be one, but Evol coldly warns him to keep his questions to himself.

After Mad Rogue was defeated by Build Genius Form, Evolt arrived and noted he was previously unaware of the existence of the Genius Bottle before punching Kazumi, stealing the Hokuto Three Crows' Lost Bottles from him and teleporting away with Mad Rogue. Back at Faust's lab, Evolt reveals to Utsumi that he intends to use the Lost Bottles to turn humanity into the final form of Smash, Lost Smash, and have rampage and destroy each other. Utsumi then asks if this is why Evolt left the Kamen Riders alive, to which Evolt confirms his suspicions, commenting that he thinks they would make good Lost Smash.

Later, after Mad Rogue and Owl Lost Smash were defeated by Kamen Rider Build Genius Form and Grease, Kamen Rider Evol showed up in his Cobra Form to claim Kiba's Lost Bottle, stating that he intends to use it to create a new world. Evol then attacks and fights Build. After getting beat back by Build, Evol attempts to shift to his Black Hole form, but is stopped by Build, who proceeds to knock Evol out of his transformation. Complimenting Sento on the Genius Fullbottle, Evolt flees the scene to go back to Faust's base.

After Sento arranges a meeting with Shimizu Kyouichi, the first Strong Smash, Evol has Shimizu turn into a Lost Smash and attack Sento. After Build reverts him back to his original state with his Genius Form, Evol shows up as Black Hole Evol and kills Shimizu to keep him from providing Sento with any information, mocking Sento for being unable to save him. Evol Black Hole and Build Genius Form then fight, with Build managing to overpower Evol and beat him down with his Genius Finish. Proclaiming that he now understands the human emotion of anger, Evol fiercely attacks Build but is unable to do anything to his Genius Form. Evol then decides to just take the Fullbottles he's recovered and leave to go back to Faust's lab base.

Back at the base, Evolt converses with Shinobu Katsuragi, who notes that Evolt was acting more emotional than he usually does in his fight with Build. Evolt then informs Shinobu that they will have to speed up their timetable for their plans. As Shinobu completes another Lost Bottle, Evolt comments that they only have four more Bottles to go before they can "create a new world". Shinobu then asks Evolt why he killed Shimizu, as he was the last candidate they had to become a Lost Smash, to which Evolt informs him that Shimizu was spilling too much about their plans, and that they can use the Kamen Riders to create Lost Smash. Utsumi then walks in and Evolt tells him to speed up the production of Lost Smash before remarking that he has "a nation to unite".

Black Hole Evol then leads an attack on the Touto government office along with Kamen Rider Mad Rogue. While Mad Rogue and a pair of Hard Guardians fought Kamen Riders Cross-Z Magma and Grease, Evol faced off against Sento and Gentoku. Sento angrily asked Evol where his father was, but Evol pretended not to know. After fighting off Build Genius Form and Kamen Rider Rogue, Evol generated a black hole and used it to annihilate the Touto government office before departing along with Mad Rogue.

As Seito occupied Touto's territories, Evolt disguised himself as Masakuni Mido and gave a speech that was broadcasted across Touto, Hokuto and Seito, where he declared that he would unite the three territories and build a new Japan. After his speech is finished, Evolt tells Utsumi to procure the Kamen Riders so they can create Lost Smash from them. However, Utsumi points out that mass-producing Lost Smash and having them attack people would trigger the downfall of the nation and questions Evolt as to what he really wants, but Evolt tells Utsumi not to ask anymore questions about stuff he's not ready to know yet if he values his life.

Personality
Blood Stalk displays a disturbingly flippant demeanor, casually carrying out his duties as a Faust strategist and enforcer even when they involve committing atrocities. He generally acts more friendly when compared to Night Rogue, though he is just as sinister and ruthless as his ally, if not more so, turning a child into the Ice Smash just to show off his Steam Blade's ability to create Smash. He is also incredibly manipulative, and willing to play both his allies and enemies alike to achieve his goals.

Blood Stalk's cruel and sociopathic traits becomes much more highlighted as the series progresses, with him eventually being revealed to be Evolt, the entity that annihilated life on Mars. He becomes much more wrathful as Vernage and Sento continue to impede his plans, choosing to keep Sento around rather than erase his personality after he possesses him just so he can witness him harming his friends.

He also shows an apparent disdain for technology and innovation, claiming to Sento that science causes society becoming complacent and ultimately leads to war, though this may just be him trying to screw with Sento, as Evolt is shown advancing technology for his own purposes many times throughout the series.

Trivia

 * Initially, the true identity of Blood Stalk seemed to be Soichi after the revelation in Episode 13 and 14. However, in Episode 30, it was hinted that Soichi was possessed by some entity assumed to be Evolt. In Episode 33, said entity was confirmed as Evolt the whole time, including the time he was posing as Blood Stalk, making Evolt the one posing as Blood Stalk instead.
 * Evol is the second snake/cobra-themed Kamen Rider since Kamen Rider Ouja.
 * Evolt has many similarities with traditional depictions of the Devil, being a manipulator who makes deals offering power to others only to eventually screw them over. Adding onto this, he has a cobra-theme as Blood Stalk and Kamen Rider Evol Cobra, similar to how the Devil appears as a serpent in the story of Adam and Eve.
 * Evolt is similar to General Xaviax from Kamen Rider: Dragon Knight. Both are extraterrestrial beings who masterminded the events of their respective series, destroyed a planet, manipulated the Riders to further his goals. They also have the ability to assume human disguises and ability to possess a human host.
 * Evolt has a habit of saying "Ciao" as his farewell phrase, though he is not the first villain to do this.