Devil's Playground

Playground One (遊び場1, Asobiba Wan) are a series of laboratories that conduct experiments and perform modifications on young children. In these laboratories, children would be tasked to fight and terminate the other children partaking in the game in order to determine the strongest test subject. The winning test subjects would then be sold to the highest bidding person, whether it be to serve in a pirate crew, be a slave to a kingdom, or a member of a noble family. Many of the Playgrounds were destroyed by the leaving only five in total. Playground One is also the name for a laboratory located on an unknown island which was plagued by storms. It is the largest Playground to be created.