Koya Ashihara (芦原 倖乎) is a second-year student at Private Tensho Academy, marked by the green tie of his grade. He sports medium-length salmon hair tied in a ponytail, with long bangs covering the sides and middle of his face, held by two clips on the right side, and has teal eyes. His standard uniform consists of a white undershirt, a dark purple cardigan with gold buttons, green pants, and black leather shoes, sometimes layered with the academy's black jacket.

As president of the Broadcasting Club, Koya frequently announces school events. He self-identifies as "Tensho Academy's Natural Speaker," embodying a talkative and sociable nature. He finds silence uncomfortable and dislikes cockroaches. Fashionable items and pasta, which he names as his favorite food, interest him.

The Broadcasting Club comprises only two members: Koya and Seijun Yuyama. Koya exhibits a strong attachment to Seijun, insisting the club remain exclusively their partnership, often calling them a "combi" despite Seijun's reluctance. Koya typically initiates plans or conversations, with Seijun participating reluctantly, yet they maintain a close friendship and are regularly seen together.

Within the anime, Koya appears in Episode 4 ("Abandone") introducing himself on the school broadcast while reporting on unusual large stones appearing on campus. He also features briefly in Episode 12 ("Piacere") during a school-wide chorus sequence amidst student riots.

His name "Koya" combines the characters for "luck" (倖) and "question mark" (乎), while "Ashihara" derives from "reed/bullrush" (芦) and "field/plain" (原).