(MOMO)
Jung Jena (YOU) had Gone missing for the last 9 years when her flight from America to Korea had crash....for the last 9 years......no one knew if Jena and her mother had survive the crash and that she was alive and spending her life at Japan where she was found....

With new identity she is now named Hirai Jun and was adopted by the family who found her at the shore of the sea.....
The family had one daughter Name Momo and  they are treated as sisters......But she and Momo had a deeper relationship.....they are secretly a couple
Momo and her got accepted at this dance studio at South Korea where they applied.....

But little did Jun know that coming back to Korea is gonna change her life again.....

(MINA)

Jung Jena (YOU) had a summer vacation at America one summer......for her having a vacation there is a boring one because she just wanted to stay in Korea and spend her summer vacation there...where she will be comfortable but she needs to go to meet her father who is dying.....she doesn't want to after her father left them when she was just a baby.....for her she doesn't have one.....but her anger turn to sadness seeing her own father slowly dying at his bed....she learn to forgive him slowly during the days that she was spending there and along the reason that she learn to forgive is the urge of this one girl same age as her (10) Mina......
The days in America became interesting as she spends it with her new found friend.....
Her father died at the end of summer......

One day before she leaves she talk to Mina and promise to come back and wait for her because she had something to say to her even if Mina wants to know Jena just said that it's not yet the proper time for it.....she left with a smile on her face......

But something happened.......

"No matter how far you are and no matter how long i haven't seen you still you are that person that i always think of seeing everyday just to know what you promise  to say......i want to be with you always and i know that you are that person that i had fallen in love with 9 years ago" (Mina)

"Don't leave me, you promise that you will always be at my side no matter what happens...you know how much i want to be with you always ....i dont want to be  your sister i want to be your everything so dont you dare leave me.....because i love you so much" (MOMO)

But Jun suddenly remembers everything that all her memories came back and the problem was that she came back to being Jung Jena as a 10 year old....and all her memories after the plane crash 9 years ago vanish like the wind.....

She forgot Being Hirai Jun and most especially who Hirai MoMo is to her life.....