All Max wants is to become a climber and search for his long-lost sister. But citizens aren’t allowed to climb - they aren’t even allowed remotely in the vicinity of the mysterious and magical tower. Plus, even if citizens could enter, it didn’t change the fact that Max’s body is paralyzed from the waist down, confined to a wheelchair. No way would anyone let him enter the tower. Ever.

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?

Nathaniel's bus ride was supposed to be just another boring commute. Wrong. Now, he, 23 fellow passengers, and a corgi named Biscuit, are stuck in a "Hell Difficulty" Tutorial, battling monsters and leveling up to survive. Easy difficulty, anyone can handle. Normal difficulty, you've got to put up a fight to get by. Hard difficulty is where only the tough ones last. And Hell? That's where you have to be a bit out of your mind! With his terrifying talent for mana manipulation, Nathaniel decides to invest every stat point into mana.

One day, six towers appear on Earth. Each one stands hundreds of stories tall, and are invulnerable to all attacks. At the base of each tower is a portal, welcoming in all who dare enter it. All sorts of magical monsters can be found inside the towers. Even treasure, magic and superhuman strength can be acquired. The problem is that the towers aren't a friendly place. Even worse, the towers sometimes release waves of monsters to attack Earth. In the year 2083, there are only a hundred survivors. In one last attempt, they challenge the final floor without regard for their lives.

Michael finds himself in the realm of the Forever Kingdom, with no memory of how he got there and who he is. Even so, he must participate in the Grand Game and forge a new destiny for himself. Dropped into a dungeon of monsters and strange magics, would you survive in a game where to lose means death? Alone, and with little more than his wits to aid him, Michael must advance as a player, slay his foes, and gain experience. All while navigating the intrigues around him and discovering his purpose.