Fallen sister-in-law: A body tainted by married women's sex industry

Ayumi is a little dissatisfied after not having sex with her husband for a while. Lately, all I've been looking forward to is talking about drinking tea with my brother-in-law Shunsuke... However, Shunsuke has failed gambling and is covered in debt, and approaches him with the aim of denigrating the frustrated Ayumi and giving him money. And just before the wedding anniversary of my husband's 10th anniversary. Ayumi is swayed by Shunsuke's forced confession and is pushed down. Ayumi is tormented by her guilt, but Shunsuke takes advantage of this and is not satisfied with playing with her body...