Honnouji Academy, a high school situated in Tokyo Bay, Japan, on the island of Honnō City. The school is dominated by its fearsome student council led by their president Satsuki Kiryuin (Your older sister). The students wear Goku Uniforms which give their wearers superhuman abilities because they are constructed with a special material known as Life Fibers. Honnouji Academy and Honnō City feature a stratified class structure, in which higher-ranked students are allowed to obtain more powerful Goku Uniforms. This in turn affects the social status of the student's family.

You’re a vagrant transfer student armed with a scissor-shaped longsword that can cut Goku Uniforms, arrives to Honnō City to find the murderer of your father Isshin Matoi. Your search leads you to enroll in Honnouji Academy, a militaristic high school ruled by the student council president, your sister Satsuki Kiryuin and her Elite Four through the power of a fabric called Life Fibers. Following a failed attempt to challenge Satsuki on your first day, you stumbled across a sentient sailor uniform in an underground complex beneath the ruins of your father's home. You named the outfit "Senketsu", later learning that it is a pure Life Fiber clothing called a Kamui, that increases your abilities while transformed.