Just before a date with Osanai, Kobato runs into Kengo, who shares some disturbing news and leaves a strange message. Together with Osanai, Kobato tries to solve the mystery. However, shortly after, it appears that Osanai is in great danger.

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.