Akane Nishikawa, the protagonist, lives alone until she meets Ryuji Sada, a man who moves in next door. Ryuji is an incredibly attractive, sexually aggressive guy with a muscular build and an enigmatic charm. Initially, Akane sees him as a cold, unpleasant man after he treats her best friend, Ai, poorly. However, her feelings toward him begin to change after a certain incident reveals a secret side of him—one he only shows to her. As she becomes aware of his deeper, more complex nature, Akane starts to develop intense, fluttering emotions. Living next to him transforms her everyday life into something entirely new.