Your little sister, Natsuki, suddenly shows up in the middle of your busy days. Apparently she came to take care of you while she was on her summer vacation. This is the story about you and Natsuki one summer

It's been quite a few days since Natsuki first arrived and the fun and lively days continue. However, you start feeling anxious. Despite how pathetic you may feel, Natsuki always cheers you on. You then come to a decision..