Ai Uehara and Chiharu Kusakabe's beloved senior, Hoshino-senpai, is finally graduating. She wants to study science at a school far away, but that means Ai and Chiharu won't see her anymore. Ai struggles with the reality of senpai leaving as Chiharu battles with her own unrequited feelings...when a bold underclassman interlopes, though, things might take an unexpected turn...