Rina Tennōji is a first-year Nijigasaki High School student and school idol club member who faces difficulty conveying facial expressions, causing others to misinterpret her kind nature as unfriendliness. She communicates emotions using the "Rina-chan Board"—first a hand-drawn sketchbook, later an electronic performance screen—displaying faces like joy or determination.

She joined the idol club after a peer's invitation through Famitsu App activities, collaborating with Ai Miyashita and Ayumu Uehara. This rare collaborative opportunity delighted her. Academically strong in science and mathematics, she finds Japanese challenging. Her hobbies include technology, app development, arcade and video games, gadget operation like quadcopters, and discussing animals. She owns a pet robot cat named Aran.

At 149 cm tall with shoulder-length pink hair and yellow eyes, her image color is paper white or gray. As a QU4RTZ subunit idol, she aims to make audiences smile, hoping fan support will eventually let her reveal her genuine smile without the board. She practices direct expression and attends events like handshake meetings, though nervous without her board.

Her growth includes a solo concert at a game arcade where she performed "Tsunagaru Connect" using a custom face-hiding monitor. Supported by fellow idols, this reinforced her resolve to connect with others. High rankings in monthly popularity polls prompted gratitude to fans, and she acknowledges emerging emotions like frustration as part of her development. Her long-term dream remains overcoming limitations to share her true smile directly.