Lai Fudatsuki serves as the student council president during his second year at Kamikazari Middle School. He operates the casino "Reasonable Doubt," a front for illegal activities and a testing ground for products developed by his collaborating private weapons company. Described as charismatic and ambitious, he exhibits a cunning personality. Physically, he has pink hair and pink eyes, is often depicted with closed eyes, and wears gloves. His role positions him as a rival to the Pretty Boy Detective Club, particularly targeting their leader, Manabu Sotoin, driven by competitive ambition. Beyond school, his involvement with the weapons company includes field-testing their products. He also appears in "Mazemonogatari," a collaborative narrative intersecting with the Monogatari series, where his activities extend into other storylines.