A few months after he's been together with MC, Zen happens to meet an ex-lover, Areum Han, someone who had disappeared from his life years ago. Feeling guilty at the sight of her, he feels obligated to become her helping hand. That debt he tries to repay, however, continuously drags him into some problematic positions. Will Zen be able to relieve his guilt, or will it consume him in the end? What about Areum's side of the story? 

People say, your first love can never be forgotten.