For Chiaki, her son Koji was everything, and it was the same for Koji. The two, who had lived together in a mother-son household, were bound by a strong bond. But their overly intimate relationship had somehow transformed into something that only the two of them could understand... Koji, who wanted to have sex, asks Chiaki to break him in. It was a very natural thing for Koji, who believed that his mother would accept anything. And Chiaki didn't think it was abnormal either.