In 2018, Japan experiences its most devastating terrorist attack, known as the "Helltopia Incident." This event involves a busload of people being transformed into monstrous beings through experimentation. High school student Tsunehiko Kamijō becomes entangled in the incident. While many victims are turned into vicious monsters or evil cyborgs with superhuman abilities, Tsunehiko retains his human appearance, setting him apart from the others involved in the catastrophe.
