He left...again

Fine! If he won't help me

I'll do it by myself

He doesn't care anyways

After what happened

I went to the other side of the park to mope

Just in time, I saw Hyunseo and Jia

I can't help but cry my eyes out

I told them everything

The pain won't go away

No matter how much I try to

It remains in me

They want to help me

They say in the park, there's a tree

In that tree, there's a writing

In that writing is a roughly drawn heart

The heart has names, they even gave me clues

And sang a seemingly familiar song

Y/N-nie and Joonie are sitting on a tree

H-A-P-P-Y, Happy!

I searcheddd that tree

I smiled when I saw the writing

Suddenly, my head hurts

And I saw flashbacks

In those flashbacks, I saw a paper

A paper being held by two kids

They're chanting the song

Am I regaining my memory?

What is that paper?

Who are those kids?

Are me and Namjoon the kids?

Is the paper a special promise?

Jia told me it's in Namjoon's room

The paper is indeed a promise

Now I must know why

Why is that paper so important