Old Friend or New Friend??

Shim Sung Gi, 14 years old. She is a nerd girl who is fat also humble person. A transfer student from Korea and still in high school somewhere in Malaysia. She has a best friend named Wu Yifan that actually love her more than just a friend. Their relationship is great before a new student that is familiar to Sung Gi come and making the sweet time into a disaster time. What will happen to her? Will it be a happy ending or behind it?