On her first day of school, Yuzu sees student council president Mei kissing a teacher and at home, she learns that Mei is her new stepsister.

During their first night sharing a room, Mei kisses Yuzu; Yuzu can't get Mei off her mind, but Mei acts as if nothing happened.

After realizing that she has feelings for Mei, Yuzu attempts to make amends, but things do not go according to plan.

After confronting Mei about her feelings, Yuzu agonises over not being able to face her; the student council vice president becomes suspicious.

After Himeko claims to have crossed a line with Mei, Yuzu gets competitive; at school, Himeko and Yuzu compete to see who will eat lunch with Mei, but Mei turns them both down.

Mei's father suddenly returns home without any warning; Yuzu tells Shou that Mei's been working hard at the academy.