Song Seunghyun and Jung Soomin have been in a relationship for 3 years. Something tragic happens and Soomin ends up dead. Seunghyun says that he will never love again, misses Soomin so much, and wishes that she was still by his side. There is no doubt that Soomin feels the same but, they both can't see each other ever again. Soomin watches over Seunghyun as a ghost making sure that Seunghyun is perfectly fine and making sure that he still shows that handsome bright smile that was the key to her heart. Soomin also tries to show Seunghyun that she's still there even though he can not see her and she still loves him although her heart can not literally beat for him any longer.