Haruka Kawarasaki, a young man aspiring to be a manga artist, and Mayuko Kawarasaki, a beautiful woman who turns heads wherever she goes. They live together, share meals every night, and share their bodies. However, they are not husband and wife. Mayuko is Haruka's sister-in-law, the wife of his deceased brother. A man who continues a relationship with a woman whose heart is broken, knowing it's wrong...