It's been 3 years since I've last heard of you.

Who would have known I would see you in this kind of situation?

Who would have known that the next time in 3 years I would see you is at your funeral?...

Hana met him.

Bang Yongguk.

Fell in love with him.

Went out with him.

Was broken by him.

He disappears out of nowhere.

 3 years later she finds herself at his funeral.

There she gets his diary and realizes the pain of her loved one.