Jeongsun is a girl who is a fifteen year old, teenager that thinks friends are more important than family. Always, Jeongsun takes care of Hyunsik who acts like a kid. Hyunsik disturbs Jeongsun's life annoyingly. Hyunsik's behavior has always annoyed Jeongsun. Oneday, Jeongsun suggests Hyunsik to hide-and-seek.