Why... do you keep making me cry?

Plot: The male protagonist (Park Ji-hoon) remembers his past life. He meets the love of his life in the 21st century. However, the female protagonist (IU) has no memory of her past life. "In a past life story I can't even remember, I love you!? Are you crazy? I don't believe it, but if I did in my past life, it's not like that anymore!! (Gulp)" The male protagonist tries to make the female protagonist remember her past life, but the price for his efforts is... a broken love and unhappiness.