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 came to say goodbye to his childhood friend Satsuki, who was going back to her family’s home in Matsumoto City. However, he ended up getting pulled onto the train to Matsumoto by Satsuki. Satsuki’s home turned out to be a long-established and splendid inn. While Naoto wanted to go back to his girlfriend Ishihara-san as soon as possible, he also couldn’t leave Satsuki alone after learning about her issues with her family, so he stayed behind for one night. Since his phone was also broken, he couldn’t get in touch with Ishihara-san, either… Some light will finally be shed on Satsuki’s mysterious past, and Naoto’s daily life will be further demolished due to another beautiful girl!!