At the age where all quirks manifest, it seems as though Chisaki's dangerous and destructive "Overhaul" manifested and brutalized his parents. Alone in the world, he was adopted by the elderly head of the Shie Hassaikai, and from then on Chisaki held a deep-seated hatred of the genetic mutations which ruined his life. The psychological scars this left him with cause Chisaki to break out into hives whenever he is touched; his personality manifests this as repulsion towards germs, which bleeds into his views on quirks.