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 has started going out with Ishihara-san, the girl of his dreams. He has also started working part-time at a Chinese restaurant along with Makina, his kouhai from middle school. In an attempt to destroy the relationship between Naoto and Ishihara-san, Makina made advances toward Naoto, but he didn’t pay any heed to her and found himself exclusively worrying about what’s going on with his childhood friend Satsuki. One day, he and Ishihara-san went to a fireworks show together, but the two of them were caught in the heavy rain. Ishihara-san, as well as Satsuki, had to stay at Naoto’s home for the night. However, Ishihara-san has been jealous of Satsuki’s relationship with Naoto. Is she going to cross the line because of that?!