Winter Sonata begins when Joon-sang (Bae Yong Jun) moves to a new high school in search for his biological father. Yu-jin (Choi Ji Woo) and Sang-hyuk (Park Yong Ha) have been close childhood friends; though Sang-hyuk wants to be more than a friend, Yu-jin sees him merely as a brother.

On a trip together with other high school mates, Oh Chelin (Park Sol Mi), Jin-suk (Lee Hye Eun) and Yong-kuk (Ryu Seung Soo), Yu-jin is saved after an accident by Joon-sang. Afterwards, they become close to each other and she opens up his cold heart. However, circumstances and fate dictate that their love will never be. He abruptly disappears from their lives.

Ten years later the old High School buddies gather together to celebrate Yu-jin and Sang-hyuk's soon-to-be wedding. Yu-jin, who was deeply in love with Joon-sang, still has a fire in her heart for him even though he's been out of her life for a decade. But at the party, Oh Chelin's new boyfriend arrives, who appears the same as Joon-sang. Could it be him or is Yu-jin only dreaming?

WINTER SONATA is one of the most memorable K-drama I've watched (and possibly the drama which sparked the "Korean wave" here in Asia). A true tearjerker, so get ready your tissues before you start :p