After knowing the momories you also know that he was living in the Small world where the future self created it for his convenience and safety here. He's like a god He can control the small world and he also escapes if any Enemy he can't defeat in the outside world.
However here there is a restriction He has to leave here for about 10 years to train That is he can train Here up to 21 years of age and he can l Go outside after Training because of Simulation.
Here Small World is the Miniature version of outside world and also has half of the resources of outside world and small world can get bigger and stronger when he gets stronger and the small world may become the real world If he become a god in the outside world.