Seon Yi is alone as usual in a classroom on a summer vacation day. She meets transfer student Ji Ah. During summer vacation, they become very close and share their own secret. After the summer vacation period, Ji Ah acts cold towards Seon Yi, now she is friends with Bo Ra and leaves Seon Yi out. Seon Yi doesn't want to become isolated again, tries to befriend Jia and exposes her secret.

At an age when perhaps friends mean more than moms, 10 year-old Sun is an outcast at school. During summer vacation, she meets Jia, who is new to town. As Sun shows Jia around the neighborhood and they play at each other's houses and share secrets, they become best friends. However when the new semester starts, Jia notices a strange vibe between Sun and the other kids. Jia tries to get into the cool kids group and starts to distance herelf from Sun. Inide the perhaps more complex and delicate world of children than adults, the two girls end up hurting and getting hurt by each other.

imdb:tt5502816