Cyberse World

Cyberse is a hidden digital world in Yu-Gi-Oh! VRAINS, created and populated by sentient AI known as the Ignis. This world was under attack by the Knights of Hanoi, led by Varis. One of the Ignis, Ai, was able to keep its location hidden, before barely escaping "Cracking Dragon".

History
The Cyberse World was created by the Ignis, AI with free will, as a place of their own inside the internet, where no humans could reach it. And it is also the birthplace of the Cyberse cards.

Five years before the start of the series, Varis assaulted Cyberse with "Cracking Dragon" with the intention to destroy it. The different Ignis that protected it were restrained by Varis and thus unable to stop the destruction of their world. However an Ignis that had not been trapped appeared and forced a disconnection of Cyberse from the rest of the network, thus forcing Varis out of Cyberse while keeping its location known only to him. However, Varis, furious by this Ignis' interference, ordered his "Cracking Dragon" to capture it, which led to the AI being dismembered by the monster's jaws. This made Varis and the Knights of Hanoi spend the following years searching for the Ignis' remnants in order to find the location of Cyberse.

SOL Technology is also searching for the Ignis because without the Cyberse, their network will continue to deteriorate, having already dropped 30% by the time the series started.