The usual result of a human taking a runaway semitruck head-on is a very sudden, very fast track to the pearly gates. But for one newly noncorporeal man, there's another option: become a dungeon. Feeling sorry for the desperate angel assigned to him, the man relents. Heck, if it doesn't work out, he can always chat with Saint Peter about it later. Next thing you know, he's a dungeon. Admittedly, a small run-down, somewhat unimpressive dungeon (more of a house, actually), but you gotta start somewhere, right?

Arc was an ordinary young woman from Earth when she was summoned to an icy hell where she fought for her survival in the name of training to become a hero. Now, after defeating the Overlord itself and achieving the status of hero, she leaves with the goal of enjoying her freedom. She arrives at Arlas, a fantasy world with magic and monsters, a world with numbers, tiers, and classes, a world governed by the System that summoned her.

She wanted to be a Necromancer, but awakened as a Saint! Somehow her summoned heroes are all undead? How will the church react when their Saintess summons a skeleton in place of a mighty hero? Sofia isn’t too keen on finding out. In this world, Gods choose [Saints], and [Saints] summon [Heroes] from other worlds; everyone knows that. But Sofia had a thing for bones ever since she was a child; there’s only one [Class] she wants: [Necromancer]! When, by the whims of fate, she gets both classes at the same time, the system breaks.

I died and was accidentally reborn as an [angelic monstrosity]. So now I'm building a holy dungeon-tower that is tall enough to reach the gods...so that I can complain about it! But the humans think that I am trying to destroy the world.

Earth was invaded. Earth was conquered. And humanity was summarily subjugated, as 400,000,000 people were culled. The terrifying part was this only took the Peacekeepers a second. There wasn't even a chance for us to fight back. In the blink of an eye, questions like whether or not we're alone in the universe or at the top of the food chain were answered. We were not. Not by a long shot. Despite the mass murder, the Peacekeepers promise they're benevolent. They don't want to rule Earth. They don't want to control humanity. They just want us to stop playing around with AI and genetics.