[1] Based on the Internet novel The 4321 Days We Shared, the romantic comedy series aired on KBS2 from March 7 to April 26, 2005 on Mondays and Tuesdays at 21:55 for 16 episodes.

[2] Yoo Hye-chan (Park Sun-young) is a 29-year-old housewife who's unhappily married to a top acting star, Kang Sang-young (Ryu Soo-young).

Though she physically recovers, retrograde amnesia causes Hye-chan to mentally revert to that of an 18-year-old girl, and she finds everything around her unfamiliar.

But little did Hye-chan know that her despised and hated classmate would become an actor one day, change his name to Kang Sang-young and become her future husband.

For Sang-young, seeing his wife reliving their high school days rekindles their lost love, and he strives to mend their shattered marriage and help her recover her memory.