Naoto Watari has had his share of struggles: his parents died two years ago, and now he and his sister live at his aunt’s house. There, his desire to protect his sister earned him notoriety as “the guy with the sister complex”—which never mattered to him, as his sister always came first. But when Satsuki, a childhood friend-turned-enemy(?), becomes his school mate, Naoto’s ordinary life is thrown into chaos … and Satsuki may just be the beginning.
During the school trip in Okinawa, Satsuki told Naoto that she would only believe in him if he kissed her. Trusting her words, Naoto asks her to go on a date with him. However, despite his efforts, he just keeps missing his chance to kiss her. As Satsuki’s curfew approaches, Naoto accompanies her back to her dorm. It seems the perfect chance for him to kiss her has finally presented itself. However, what he gets instead is an unexpected turn of events that will plague his mind for a while!