Hidaka is a second-year student. Hidaka's sex is unknown as Hidaka is seen wearing both the male and female school uniforms. Hidaka is a reporter in ASP (Anti Suppression Paper), which is one of the news clubs at Takafuji Academy.

Spoiler

It is later reveled that Hidaka is actually a girl who was forced by her club to wear both male and female school uniforms so as to falsify the number of club members to obtain more funding.

(Source: ANN Forums)