Geto was originally a student of Masamichi Yaga's alongside Satoru Gojo and Shoko Ieiri at Tokyo Jujutsu High. His experiences as a jujutsu sorcerer bred a deep hatred for non-sorcerers, leading to an incident where Suguru massacred over a hundred civilians in a single night. He was expelled from Jujutsu High and came to be known as the worst of all curse users.