There is a demon castle. There is also a tomb. The monsters there are strong enough to wipe out humanity in the magical land of HEIM. HEIM is a world in a newly launched video game played by humans in earth. The game features a new technology which would allow players to fully immerse themselves in this game.  A patch update gone wrong, a ritual gone awfully well and a mass teleport gone a bit awry results in an undead lord and a demon lord along their underlings being 'transported' to the game world of HEIM. *Warning, I'm terrible at writing. I'm a bit of oblivious too.*