The work mainly tells the story of a day when a VRMMORPG "YGGDRASIL" that has set off a big craze was supposed to stop all services, but even after the end time, players will not exit the game, and NPCs have their own thoughts. The protagonist Suzuki Satoru (real name), who loves video games in the real world, accidentally traveled to a different world with the members of the "Ainz Ooal Gown" guild while waiting for the system to force log out, and he also became the strongest magician with a skeleton appearance - "Flying Squirrel". In this way, the real fantasy legend officially kicked off.