Mao is staying with her brother and his wife in Tokyo while she is job hunting. In fact, there is another reason why she came to this house that she cannot tell her family. Mao has kept the fact that she is bisexual a secret, and is excited that her wish to live under the same roof as her beautiful and intelligent sister-in-law, Reiko, has come true. Meanwhile, Reiko has no idea about her sister-in-law's lewd thoughts, and today, as usual, she sends her husband off to work...