"Since you act like such a naïve simpleton, older brother, I wonder if you even have a cock." The arrogant younger brother, Yeon, always looked down on his older brother, Kangwoo. He would do so with words like "simpleton" or "beast," and so on. However, Kangwoo, who was adopted, would always smile faintly like a scholar and quietly accept Yeon's insults.

Then one day, everything changes. "You always treat me like a beast, or rather, a eunuch... aren't you curious what that beast is like at night?" "..." "I'll show you my cock." To Yeon's usual provocation, Kangwoo finally begins to react.