My name is Ryoichi. I'm a 22-year-old fourth-year university student. One day, I suddenly found myself living alone with my sister-in-law, Arare, for 10 days. But the truth is, I have bitter memories with Arare... When we were students and in the track and field club at the same school, I fell in love with Arare, confessed my feelings to her, and was rejected. But even so, I couldn't resist the idea of living with a woman I once loved!