Osanai ropes Kobato into her plans for the summer vacation. However, the cake he is supposed to buy for her proves to be irresistible, even for Kobato.

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.