Half a year since Yusuke's father left home to go with another woman, Kana has always been tough in front of his son, but he knew his mother was still sad. Seeing the loneliness appearing on her mother's face made Yusuke feel heartbroken, but not knowing how to make her happy again. One day, Yusuke accidentally witnessed his mother masturbating. From that time, he was determined to replace his father's position, bringing happiness to his mother. At first Kana was also surprised and confused. But when she realized her son's concern and anxiety, she gradually accepted this.