Alex is your typical overworked guy that just lives day by day without planning ahead of its life, but that's until a mad wizard kills him nonchalantly when she decided to release a powerful beast to create havoc in the city. That should have been the end for him but he finds himself reborn as a Dungeon Core in the Void right attached to his home universe by a portal.

"Dungeons inside a portal" Alex is pretty sure he read one or two novels about this type of story, but now he's living this type of story... Except he's the dungeon and not the overpowered protagonist that delves them.