Thirteenth Level World

In the future world, human beings live in huge bunkers, and the minds of workers are controlled by infrasound waves. They think that the world is just countless rooms, and the ceiling is the "upper limit" of the world. However, a boy and a girl accidentally broke through the blockade. They crossed twelve levels of obstacles and finally reached the surface. The two of them continued to grow during the journey. They improved their worldview, recognized their rulers, and broke the rules of the world. When they saw the sunrise, they realized that the place they lived in was "hell". However, at the Gate of Heaven, a wordless tablet revealed a surprising truth...