It's been half a year since Yusuke's father left home with another woman. Kana has always been strong in front of her son, but he knows his mother is still grieving. Seeing the loneliness on her face makes Yusuke feel heartbroken, but he doesn't know how to make her happy again. One day, Yusuke accidentally witnesses his mother masturbating. From that time on, he is determined to take his father's place and bring his mother happiness. At first, Kana was surprised and confused. But when she realized her son's care and concern for her, she gradually accepted this.