youngjae and daehyun are neighbor and friends since diaper but they hate each other's gut to the core.

youngjae plays drum, he think classical music is boring. daehyun plays violin and he think rock music is noisy.

youngjae have a huge crush on daehyun's brother, yunho, who is a guitarist on a rock band.
daehyun is helplessly in love with youngjae's step brother, jaejoong, who plays piano so beautifully.

unlike daehyun who confessed then got rejected right away by jaejoong, youngjae is able to date his crush for awhile. through that he learned that yunho and jaejoong were dating and still in love with their ex despite that they've now broken up.