One night and two days of 1 night and left alone by my wife's sister who suddenly came over

After his wife's homecoming, Ryota ends up living alone for the first time in a while after giving birth. Feeling lonely in the empty room, Ryota welcomes his sister-in-law, Rena, who has suddenly arrived. However, Rena's true goal was to have sex with an affair. Without realizing this, Ryota enjoys a relaxed bath, and his evil hand creeps up. As Rena's beautiful face smiles, her flesh and sensual body sags and her reason is blown away...