Ren'ichi Amagi is a 16-year-old second-year student at Moriyoh Gakuen, distinguished by his short blue hair and piercing blue eyes. His handsome appearance and popularity attract the attention of every girl in the Casual Romance Club. He joined the club specifically to seek lighthearted romantic experiences.

The club convenes at the Starry Sky restaurant, where Ren'ichi partners with Nanase to match members impartially. Playful dating guidelines govern their interactions, supported by a shared notebook detailing each girl’s statistics, horoscope, preferences, dislikes, and daily reflections—all used to inform romantic pursuits. Throughout the club’s one-month duration, Ren'ichi maneuvers these social dynamics, aiming to secure a lasting relationship with one girl before the club disbands.