18+

Dae Ho, who became an orphan at the age of 13, was adopted by his father's friend. However, Dae Ho in adulthood knew nothing about the relationship between men and women. Aunt and sisters decided to give pure Dae Ho a secret class

Keita Suminoe has two older (not blood-related) twin step-sisters who love him in a lustful way and have no problems expressing it. They even like to compete about it; much to the laughter of his friends (which he usually endures without problems). O