Hidaka Shiohama is a second-year student at Takafuji Private Academy who works as a reporter for the Anti Suppression Paper (ASP), one of the school's news clubs. Shiohama's initial gender ambiguity arises from being seen wearing both the male and female school uniforms. This practice was mandated by the ASP club, requiring Shiohama to alternate uniforms to artificially boost the club's membership count and secure more student council funding. It is later revealed that Shiohama is female and participated in the uniform scheme under club coercion, not personal choice.

Physically, Shiohama stands 161 cm tall and weighs 46 kg, possessing an androgynous, slim build often noted for its pale complexion. Shiohama has short ochre-blond hair with spiky bangs and straight strands, along with grey eyes. The primary attire is the Takafuji Academy uniform, switching between male and female versions as part of the club's plan. Secondary clothing elements include an armband, hairpin, knee-high boots, knee-high socks, and a string ribbon tie.