Tomochika Shibuya attends Saotome Academy's idol course in Class A. Born July 7th, her zodiac sign is Cancer. She stands between 163–167 cm tall, weighs 49 kg, and has blood type O. Her appearance features long burgundy hair with a signature braided lock on the left side, pinkish-purple eyes (depicted as a purple-to-pink gradient in-game), pink lipstick, and pink nail polish. She practices boxercise and plays the electone.

Tomochika is the roommate, classmate, and close friend of Haruka Nanami, whom she met during entrance exams, insisting Haruka call her "Tomo-chan." She radiates energy and confidence, speaking her mind openly as a social butterfly. While similar in demeanor to Otoya Ittoki, Tomochika exhibits greater intensity. She consistently champions Haruka, offering steadfast advice during difficulties and remaining unruffled by Haruka's distractions. This loyalty manifests in defending Haruka against classmates questioning her talent, teaching her music reading, and providing emotional support.

For musical assignments, Tomochika partners with Yajima Daiki after their pairing by instructor Ringo Tsukimiya, calling their collaboration a "match made in heaven." She frequently shares meals and leisure time with Otoya Ittoki and Haruka. A subplot involves undisclosed family issues leading to a temporary academy departure. Her idol activities include co-designing and creating performance costumes for STARISH with Ringo Tsukimiya.

Her background details are limited, though her name holds symbolism: "Tomochika" blends "knowledge/wisdom" (tomo) and "humility" (chika), while "Shibuya" references both persimmon juice and Tokyo's fashion district. She aspires to master singing, acting, and all aspects of idol performance.