"If we learn how to love, we must learn to let go."

Sae Na is just another somebody of his past. The past that no one has seen.

She is just another normal girl in his life. The life he doesn't want to show anybody. 

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But now, time has changed.

He is no longer that boy from the past and she too is not the same girl.

Everything has changed;

Except their feelings for each other.