Maki and Mizuki, who live on the same floor of an apartment building, are once again chatting away about their sexless marriages with their husbands. Meanwhile, a young man named Yamada has come to Tokyo and lives on the same floor as the two married women. It doesn't take long for Yamada to pounce on the two married women, as he is a perfect match for them. That same day, Maki helps Yamada unpack his belongings and then goes over to his house, while Mizuki comes over to share dinner with him. The reverse threesome that began with the frustrated married women is just the beginning of a dream new harem life...