A brother-in-law who decided to live with his younger brother and his wife for a while due to work reasons. In fact, the younger brother and his wife, who live in peace, are dissatisfied and lonely with their husbands who are not trying to make children. The brother-in-law who sensed such a heart approaches Yukino instead of his unhappy younger brother. Yuki refuses to be unfaithful, but the pleasure cannot be suppressed by the repeated blame of her brother-in-law’s cunnilingus and she has a relationship. Yukino, who was fascinated by the gentle and rich caress, seduces her brother-in-law and drowns in an unfaithful relationship.