During a class assignment, a vase in the cabinet seemingly breaks by itself, but there's an elaborate plan behind it. However, this mystery is quickly forgotten when Osanai sees the bicycle thief again and plots revenge.

When Kobato goes to visit Osanai at her home to invite her to eat candied apples, he learns that she has been kidnapped. Just as he leaves the apartment, he receives a mysterious message from Osanai and, with Kengo's help, sets out to find her.