Pei-pei is a junior high girl, who is often trapped in the classroom with Yi-shian, a boy hardly seen around school. Though they are in the same classroom, they are in two different worlds.

One day, a failure in competition makes Pei-pei feel awful. Through Yi-shian’s encouragement, she climbs over the school’s fence to explore a new world.

Pei-pei has a hard time to keep calm because of constant depression and anxiety in her puberty. There is no exit to vent her forbidden desire and voices that should not be heard. Is the outside world really as wonderful as she imagined? Will Pei-pei be able to find the way after crossing the wall?