The Natural Enemy Apocalypse

The world is in crisis. Humanity faces a tremendous threat, and those caught in the disaster have come up with an idea to change their circumstances: summon people from other worlds to help them.

The summonings resonated with one another, merging an untold number of worlds together.

But just as drawing on a rotten apple produces another rotten apple, a world where humanity is in peril can only summon another world where humanity is in peril!

In a world of swords and magic, the Demon King rules all, and nineteen Demon Generals hold sway over their own domains. In the future, AI has rebelled, iron men have gone rogue, and the out-of-control robots are set on wiping out every human. In a primeval world, savage giants rampage across the land, forcing humanity to flee in every direction. In a world of heroes, bizarre beings keep appearing in ever greater numbers and growing stronger, as if they might crush everything beneath them. In a world of urban legends, terrifying balloons drift through the sky, fish bear human features, and women have whirlpools for faces. More and more supernatural phenomena and indescribable monsters appear in that world...

And even humanity may not be as simple as it seems!