In the Prime Kingdoms, the system dominates everything. It dictates one’s strength, skills, and power. It spawns dungeons and guides the actions of their monsters. But every system has its limits, and it’s about to push four oddball adventurers to theirs.

Ten years ago, Amelia woke up alone and lost in a broken world where she had to fight for her survival. Now, after reaching the pinnacle of power, defeating the Void itself, and escaping the abyss, she has finally found her way back into the real world. But instead of returning to Earth, she arrives in the land of Vacuos. A fantasy world with magic, monsters, Classes, and Levels. A world that is governed by a System like it were a video game.

On a typical day, on an average train platform, two warring sister goddesses found their avatars. One avatar, the young Yoshi, was swept away to the world of Ephemera to be a great hero of honor, courage, and light. The other, the not-so-young Seiji, was swept away to become a dark lord out to kill or conquer all in his path. But Seiji is in absolutely no mood for that nonsense. It's bad enough that on Earth he was a closed-off, misanthropic grouch with zero patience for other people. Now he's supposed to muster enough of a give-a-damn to lead vile hordes?

When it comes to action and adventure, every hero needs a good sidekick. Holmes has Watson, Batman has Robin, and Daniel has . . . Orrin. More like brothers than friends, they always have each other's backs. And as Daniel is the big, strong, handsome type, Orrin is more than happy to remain in his shadow at school, at parties, pretty much everywhere. Then things take a turn for the truly weird when a terrible accident catapults the pair into a world totally unlike their own, in which the rules of a role-playing game hold sway.

After his parents died, Alex Roth had one desire: become a wizard. Through hard work, he was accepted into the University of Generasi, the world’s greatest academy of wizardry.... Fate, however, had another plan. On his 18th birthday, he is Marked by prophecy as one of his kingdom’s five Heroes, chosen to fight the Ravener, his land’s great enemy. But his brand is "The Fool". Worst of the marks.

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.

Arthur lives with his father, a fallen but proud former noble, in Border Village #49, along with the other good folks condemned to toil in service to the Baron. But Arthur has an edge: a stolen heart card that secretly fell into his possession, thanks to a dragon. It’s a priceless source of power for the Baron and the tyrant will kill to get it back. Invaluable, too, to a young man of spellcasting ambitions.

Silas is inducted into the System, becoming the last in a long line of Earth's "forerunners." The rewards are great, but the danger is greater. We are not alone in the universe. The fate of five worlds hangs on how their forerunners perform. Will Silas have what it takes to win Earth a place in the multiverse? Or will Earth become another mining world stripped of all resources and left a barren husk floating in the cosmos?

Felix's life on Earth had become a series of dead-end jobs, ruined relationships, and rotating apartments smaller than most postage stamps. By all accounts, even his own, he was a coward. Too afraid to move forward, to take risks. Yet when given the chance to choose between risking his life or walking away from a deadly encounter, he didn't hesitate. Moments before his untimely demise, Felix was snatched from earth and thrust into a magical world known only as "The Continent". Empowered by the "System", he learns that he can strengthen himself through combat and dedication.

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?