While I like this villain, I'm honestly even more surprised to see he still "alive" even after his arc ended. So let's go for it. The name Isaac Ray Peram Westcott is pretty much very known among us in Villains Wiki and Tv Tropes for a good reason, he is so far the evilest of all Light Novel villains to date.
And guess what... he returned as a CUTE LITTLE GIRL WHO IS A GOOD EXAMPLE OF A WAIFU-MATERIAL.
The thing here is that he just returned in a new media, now going by the name of "Kaguya Yamai", one of the main heroines of Date A Live franchise in a new crossover game between Date A Live and the light novel, manga and anime series "Is It Wrong to Try to Pick Up Girls in a Dungeon?" which is one of the most popular LN series in Japan nowadays.
The setting?
From one side, we have Date A Live. The story is set in an alternate Earth where phenomena, known by the generic term "Spacequakes", occur. The first of these spacequakes devastated thirty years before the time the story takes place, claiming 150 million lives, an tragedy started by the Isaac Westcott, the villlain being proposed here. Enter Itsuka Shidou, a young man of above average skill in school but no experience with girls. By accident he stays near the area that was just ravaged by a space quake, only to find a girl in a warrior dress who threatens to kill him. Before he can say much, she disappears. Afterward he learns that she, among others, is a spirit. Spirits come from another world and cause destruction whenever they enter the human world. Shidou is now given a choice to see how the military kills spirits, or take another option: date the spirits, make them fall in love with and surrender their powers to him so they can live among humans without fear of being hunted.
And from another side, we have Is It Wrong to Try to Pick Up Girls in a Dungeon? The story takes place in the fictional city of Orario to when gods all came down seeking excitement, limiting their divine powers to perceive and experience the hardships that thrives on the lower world. Offering mortals to fight monsters assorted in an underground labyrinth known as Dungeon. Adventurers visit the dungeon to defeat monsters and take their crystal shards, which are used to craft magic items, among other treasures; however, they can also be exchanged for the world's currency. The people of Orario join groups called Familia, who serve a range of functions from dungeon crawling to crafting items. Each Familia is named after and serves a resident deity. In a fashion similar to role playing games, the adventurers are grouped into levels, increasing their levels and abilities according to their achievements.
And turns out, both of the said worlds are connected by mysterious reasons and a few heroes of Date A Live universe are teleported to Danmachi's universe... under the manipulation of THIS villain...
Who is he/she?
It's useless to talk more about Westcott from this point on. The guy is just that vile... anyway, our villain here is Kaguya Westcott, a Spirit born from the mana of all other Spirits sealed by the main hero of DAL universe, Shido Itsuka. Kaguya "Yamai" was born as a non-corporal entity but soon adopted the form of the heroine Kaguya to continue living... while she was born innocent, she felt ADMIRATION for the atrocities and ambitions of the main antagonist, Westcott, and and by her own free will, decided merge herself with Westcott's persona, copying him and consequently becoming HIM in the body of a Spirit. From there on, we have our new Westcott... even more insane than before.
What she has done?
After becoming Westcott, our new "Westcott", now reborn as Kaguya, discovered the existence of other multiverses using the power she stole from other Spirits and decided to set herself as the rule of all existence by destroying the entire multiverse and killing all Gods of the existence. To start her own plans, she begins merging two worlds at the same time together. These "mergings" lead to catastrophic damage across both of the merging worlds, while also creating phenomenon that summon monsters in both worlds. These alone lead to the deaths of thousands of innocents on various worlds.
After merging the worlds, Kaguya managed to open a portal between the worlds and teleported the heroes of DAL universe to the Second World: Kurumi Tokisaki, Shido Itsuka, Origami Tobiichi, Kotori Itsuka and Tohka Yatogami. After sending the said heroes to a dungeon filled with monsters, she took the form of Kurumi Tokisaki and attacked a party of adventurers near the dungeon, killing half of its squad and using her clones to torture, mutilate, abuse and DEVOUR most of party alive with the solo purpose of incriminating Kurumi and other Spirits to the people of that world.
After passing the impression that all Spirits are monsters, she manipulates the Loki Familia, the guild responsible for sending adventurers to that dungeon and forces the main heroine of Danmachi's world, Ais, to fight Tohka to death while her other party members subjugated Bell and Shido. While the said heroines were fighting, Kaguya invades Ais' mind and discover she was a troubled person with psychological problems and a dark past full of tragedies and abuse. She then began to explore her fears and past while merging her with a Sephira Crystal to turn the heroine into an Inverse Spirit, locking up the pure heroine inside of her mind to see and feel the suffering and cruelty she experienced in her entire life for decades.
When the two heroes begins their mission to rescue Ais, Kaguya immediately summons an Inverse Ais on the middle of the city, allowing them to save her. When the heroes finally managed to free Ais from her inverse form, Kaguya takes all the pain and suffering she Ais lived and threw back at her, resulting in her second Inversion; causing destruction to entire planet, killing billions.
However, to make her plans come to life, she needed Ais alive and so she took the form of Kurumi and returned to the past, to where the heroes could have a new chance to save Ais without breaking her Sephira Crystal, something is going to need if she wants to become the new God (Demon Queen) of the multiverse. When the heroes finally managed to save Ais from herself without breaking the Sephira Crystal, Kaguya and her plans were exposed by Kurumi, who then, finally, showed her true colors.
Kaguya reveals her true identity, including her own will, that is Isaac Westcott. Little by little, she express her true plans and how much she hated them. She then stated her true goal was to destroy the multiverse, "squeeze" the lives of all octillion living beings living in it in front of the Gods before turning the Heavens in a paradise of flesh and blood. When Lilirica, one of the main heroines of Danmachi cried and asked why Kaguya was doing that, she simple replied saying she was just pretending to be her sister and regretted for not killing her and cutting her head off due to her innocent personality. Before they could fight, "Westcott" taunts the heroes and states he is going to fight them in the form of Kaguya, a form Shido and his friends, can't hurt for being a close friend.
With the Sephira Crystal pure, Kaguya proceeds to absorb the Sephira Crystal of Ais in herself, ripping off her soul and becoming an Inverse Spirit. As a Spirit, she begins to cause spacequake around the planet, causing the death of millions just to test her new powers. When the heroes are battling Kaguya Westcott, she begins to torture Bell in front of his friends by breaking his bones and ripping his skin. She then proceeds to summon a storm of darkness that destroyed the town they were in, making thousands of victims.
As a final act to end that battle, Kaguya tries to cut the head off Shido but she ended defeated anyway. In her final moments, she laughs insanely as she embraces the Shinigami sending her soul to Hell.
Freudian Excuse or other redeeming features?
Nope. None. You may consider she is "brainwashed" by Westcott's will but the "original Spirit" ceased to exist at the moment she became a clone of Westcott by HER OWN FREE WILL, basically becoming a new Westcott but with a different body and objectives. She is Westcott but at the same time, she isn't as she is a different entity with different ambitions... not to mention, she was even more insane than Westcott.
Heinounsess?
If we consider the heinous level of both worlds, she EASILY pass even if Westcott is on the line. However, since it's a non-canon game, the heinous level of both worlds are null in this game. Anyway, she is ultimately responsible for literally every bad occurence in-story, she is the solo main antagonist, and has a succeeded + attempted bodycount measuring in the BILLIONS/OCTILLIONS (something you cannot find easly in fiction). With that said, she easy pass.
Conclusion?
She is Westcott... for me... this is enough.
