Our Neighbor, Miss Yae

Original title: 隣の八重ちゃん

Keitaro is a law student and Yaeko is a high school girl. They are neighbors, and their friendship is starting to develop into something more romantic. Then, Yaeko's sister Kyouko has a breakup with her husband and returns home. Kyouko is clearly interested in Keitaro and Yae becomes anxious.