Kai is a reserved and antisocial individual obsessed with restoring the world to a pre-Quirk state. He leads the Shie Hassaikai and believes Quirks are a plague on humanity. He views the use of Quirks, regardless of intent, as a sickness. Driven by his ambition to eradicate Quirks and restore the Yakuza's power, he displays a strong determination and an inflated ego, believing himself uniquely enlightened. His methods are extreme, and his reliance on his Quirk, Overhaul, which allows him to deconstruct and reconstruct matter, is significant.