The dark prison merges with reality, and strange creatures invade the world through the door. An organization was quietly born, and they called themselves the Prison Keepers. They keep the weird outside the door and capture and contain the weird creatures that run into the world. Lu Xiao accidentally fell into the dark prison and lived alone in the dark prison for three years. After being discovered by the prison guard organization, he was taken away from the dark prison and became an organized S-class container.
