Yeonjun is a young man with a difficult character, accustomed to solving his problems with aggression and stubbornness. He is an evil, toxic, problematic abuser who does not know how to solve problems without fighting and violence. His relationship with his ex-girlfriend is ruined by his impulsiveness, and at one point when he runs into the guy who is now dating her, Yeonjun starts a fight, which worsens his reputation.

At this point, Beomgyu, Yeonjun's best friend, comes to the rescue, having been observing his problems for a long time and decides that the time has come to change his behavior. Beomgyu decides to help Yeonjun become more mature and confident by showing him how to have healthy relationships and prepares a series of lessons to help his friend blossom into a gentleman and romantic.