Satomi (Chitose Hara) lived a happy life with her beloved husband, Koichi. Koichi, a beloved wife, bought an apartment in the suburbs and is working hard to repay the loan. Nobuo, a brother-in-law who will live together for a while for job hunting. Nobuo, who had been aiming for Satomi's body for a long time, succeeds in having a relationship with Satomi one day. Satomi's lust blooms on that day. Despite Koichi who does not notice the relationship, the unfaithful act of immorality continues ....