It all starts when Joon-Sang , a mysterious boy, joins Yu-Jin 's class . He is there to find his biological father. They slowly fall in love with each other, which doesn't please Sang-Hyuk , who has been in love with Yu-Jin since he was little. At the same time, Che-Rin , another girl in the class, does everything she can to seduce Joon-Sang, without success.

But one day, Joon-Sang, who is on his way to go on a date with Yu-Jin, gets hit by a car
and suddenly disappears from their lives.

Ten years later, Yu-Jin and Sang-Hyuk gather their friends and have a party before their upcoming wedding. But when Che-Rin introduces her new boyfriend, everyone is stunned to see that he is exactly a copy of Joon-Sang.