The arrival of new music teacher makes a big difference for a group of troubled high school students.

The story of two brothers, the younger one of whom has a rare disease which causes his body to age rapidly while his mind is still in a pre-teen state.

Young-Hoon works for his mother’s restaurant, but he prefers hanging out with his friends. He then meets Yeun-ah, a tough lady that works in a room salon as a barmaid. She takes the initiative by coming to his restaurant, when he is working, and propositions him in a playful way. They become a couple, but their relationship is always volatile. They fight constantly (physically and verbally), but the next moment kiss and make up. Meanwhile, Young-Hoon already has another girlfriend, who is his finance!

Ji-eun has a bad impression of men due to bad experiences with her father but her mom Hyeon-ah convinces her into getting tuition from an art student. Jeong-woo is surprised at how cold she is towards him but at the same time, there's tension between the two. Meanwhile, Hyeon-ah, who is afraid something might happen between the two, calls Jeong-woo in and suggests something but he confesses his love for Hyeon-ah instead. They have fallen into an unappropriate relationship and Ji-eun decides to give her mom a surprise.

Despite their different family backgrounds, four friends grew up together in the wearisome years of the 70s. But as time goes by, each of them takes a different life path.