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.
Naoto learned that Satsuki is going on a school trip in Okinawa like him. Driven by his emotions, he tried to sneak into her room, but was caught by a patrolling teacher. Determined to see her no matter what, he teamed up with his ex-girlfriend and his group's leader to carry out a daring plan!