He sees her one day busy folding some kind of paper. He goes to her and asks what she was doing.

She looks at him, and goes back in folding the paper. "Paper hearts." She smiled. He takes a chair and sits beside her as she continues folding.

"Someone recently told me that paper hearts are no different from our hearts; easy to break, easy to rip apart, but difficult to put back together again." She said, finishing one heart. He could tell that this was her first time making it for he could see the imperfections in it. But he just smiles and takes it from her hands. She tries to reach for it, but it was too far for her to reach and she just takes another sheet, folding them.

He figured out she was drawn into her work and he leaves her, putting the paper heart she made in his pocket. Since that day, he tried studying how to make those paper hearts.

He lay in bed, staring at the paper heart she made. He managed to keep it alive even after all these years of separation. After discovering he still had that picture of frame, he decided to reminisce on the past.

"Heejin." He said, calling her after classes.

"Yes?" She smiled. 

He hands her over a paper heart made out of scratch paper. She stares at it for one moment and laughs, and he felt ashamed. Did I do something wrong? He thought, staring at the paper heart he made.

"I made it for you." He smiled.

"Me?" She asked, dumbfounded, taking it from his hand.

A smile paints across her face, looking at the paper heart. She looks at him and thanks him.

"Rip it." He said.

"What?" She asked, looking back at the paper. She then rips it apart, it's pieces falling on the floor.

"But--"

"That was my heart." he said, and her jaw drops. For some reason, she wanted to fall down on her knees and pick up the pieces, one by one. 

"I'm sorry," she mutters. He pulls out another paper heart from his pocket and gives it to her. She hesitates for a while, then takes it.

"Paper hearts and real hearts are different from each other, Heejin," he explains, placing his hand on the side of her cheek. She freezes and looks at him. "they're not the same."

He puts his hand down, afraid that the situation might get more awkward. "I'm giving that to you, and I want you to take care of that." He walks away, leaving her speechless for one minute or so.

He picks out things from his "memory box" containing his old school I.D., his report card and some letters and pictures from his friends. He ignored his groupmates who constantly barged in their room. All he cared about was looking back in to the past. As he read the letters and notes, he couldn't help but laugh and smile to himself. He chose to read Heejin's letter next, and he was surprised to see a pink paper heart instead of a letter. Nonetheless, he takes the paper heart out and reads the writings on it.

Here's mine. Since I have yours, I want you to have this Please take care of it, okay?

He doesn't bother reading the other letters, and if there was an actual letter from her envelope, he doesn't read it. He keeps it on his closet and takes the paper heart with him.

I'll take care of it, he thought. In fact, I've been taking care of it ever since.