They first met while they were in 2nd grade, an incident where Mimi saved YooA from a few boys from their class who kept on disturbing YooA. Mimi was known as 'FattyMimi' among her classmates because she was round and chubby while YooA was known as the Doll like Princess that every boys in the class had a crush on her.

Since then they became best friend, an inseperable duo. Eventhough the boys didn't dare to disturb YooA anymore but that didn't stop them from calling Mimi, 'FattyMimi' Unfortunately, one day Mimi disappeared without any words, which left YooA hanging in confusion. YooA just knew that Mimi had moved to the States and no one seems to know whether Mimi will ever comeback. 

The last conversation they had before Mimi left was a promise to each other to love themselves and never change no matter what. YooA tried to hold on to that promise and all the memories she had with Mimi for as long as she could as she didnt want to lose her first precious friendship ever. 

But the question is how long? Will they keep that promise?