Kai is a mysophobic, antisocial sociopath who is obsessed with returning the world to the way it was before the Quirk phenomenon. Due to a combination of an old theory claiming Quirks derived from rats and his own mysophobia, Kai believes that Quirks are actually a plague on humanity, having infected people with "syndromes" of heroism and villainy. He looks down upon those that use their abilities for either purpose, referring to acts of heroic sacrifice.