"Sorry for suddenly coming in. Can I come in?" While his wife was visiting her hometown, his sister-in-law, Akari, came to check on him. Tatsuya, who had been doing the housework alone and feeling lonely, welcomed Akari in, but... Tatsuya was taken aback by Akari, who got strangely close to him. Just being stared at by her lovely beauty made him aroused. He tried to calm Kokoro down by taking a bath, but Akari came to wash his back and they ended up sharing a bath together...