Asa Mitaka is a high school girl who doesn’t seem to fit in. She watches her classmates live a carefree life, hang out with friends, have fun and can’t help but hate them.One day, her teacher Mr. Tanaka brings a Chicken Devil named Bucky to class, explaining that in three months the class will kill and eat him to teach them how precious life is.Three months pass and Bucky becomes something of a student mascot. Everyone seems to love him except Mitaka. When the student council president joins her, she retreats to the school roof to eat lunch. The President notices how upset Mitaka is with Bucky and assures her that he’ll be dead in about 100 days so there’s no point in worrying about it.Mitaka goes on to talk about how the city they live in is corrupt. He points out that there’s a devil running around with a chainsaw playing Devil Hunter while there’s trouble around town, and to make matters worse; now there is a chicken devil in their class.As the weeks and months pass, Mitaka watches in annoyance as her classmates are chained to the Chicken Devil. Finally, three months after the day he was brought into the classroom, Mr. Tanaka reveals that they don’t actually kill and eat Bucky because it was all an elaborate lesson to teach them how precious life is, including the lives of devils. To celebrate Bucky’s pardon, the class goes out for football.Mitaka reluctantly joined them, standing aside and watching the students play instead of joining them. Tanaka approaches her and asks why she’s doing everything by herself, to which she replies that she goes to school to learn, not to make friends. That’s when suddenly Bucky jumps into his arms and calls her name. She is taken aback by this because no one knows her name except the teacher and the class president. At this point, she realizes that she hated everyone at school all this time because she was jealous of them. She didn’t realize she wanted to be like them. As Bucky inspires something new in her, she decides to finally join her classmates in the game when she suddenly trips and falls.When she gets up, she looks horrified to find that she accidentally crushed Bucky underneath her, exposing his insides to the entire class. As everyone looks at Bucky’s corpse in utter grief and horror, Asa vomits in shock and passes out.Mitaka arrives at school the next day and feels the judging looks of her classmates. She returns home completely ashamed and wishes she would die. In the middle of the night, as he sulks in his bed, he hears his doorbell ring. Outside are Tanaka and the class president, who have come to escort her to Bucky’s grave. They tell her that Bucky’s spirit might forgive them if they visited him.On the way there, Tanaka and the class president cross the street, leaving Mitaka behind. The class president realizes that it’s because Mitaka won’t cross the street without a green light and starts berating her for being a good boy. She suddenly mutates into a multi-headed muscle-bound colossus and reveals that she made a deal with the Devil of Justice, claiming that she and Mr. Tanaka were in a relationship, but he had a thing for Mitaka, which was holding them back. Because of this, the only way to be happy is to kill Mitaka. She also reveals that her plan was for Mitaka to kill Bucky to humiliate her.The transformed class president lunges at Mitaka with her claws, and in her final moments, Mitaka is at peace knowing that it wasn’t her fault that she killed Bucky after all, and that maybe if she had lived a more confident life, she might have had friends or even a boyfriend. The class president then tears up her face, leaving her on the ground with one eye exposed.At that moment, a devil in the form of an owl appears above the street lights. He tells Mitace that if she wants to live, her body will belong. Her corpse suddenly revives and rises, now claiming to be a war fiend. He attacks the class president, turning Tanaka’s spine into a sword and the president’s arm into a grenade, demonstrating his ability to turn objects into weapons of war. She claims that this battle is just her warm-up and destroys them both with a grenade.As he walks away from the explosion, he sees a poster of Chainsaw Man’s face on the wall and vows to find him and make him vomit nukes again.