My wife's own sister comes to help out when my wife is hospitalized. Reika, her husband's sister-in-law, is beautiful, friendly, and caring, and as she does all kinds of things for her brother-in-law who is all alone, the two become intimate. She is also married to his sister-in-law, but... in his wife's absence, he engages in a series of intimate and lewd acts with her! They fall into the forbidden pleasure that must never be revealed!