|Battle for the Cyberse|
Cyberse becomes a target
The Battle for the Cyberse is a major event in Yu-Gi-Oh! VRAINS involving the Knights of Hanoi and SOL Technologies. SOL Technologies wants to harness the Ignis and the Cyberse World while the Knights of Hanoi wish to destroy them.
Dr. Kiyoshi Kogami, performed several simulations of the Ignis' growth and concluded that AI and humans would be at odds and be the end of the world. Kogami then formed the Knights of Hanoi with the intention of destroying his creation. So five years before the start of the series, Varis assaulted Cyberse World" with "Cracking Dragon" and restrained the Ignis that protected it. However, another Ignis appeared and forced a disconnection of Cyberse from the rest of the network, forcing Varis out of Cyberse while keeping its location hidden. Varis, furious by that Ignis' interference, ordered his "Cracking Dragon" to capture him, which led to the Ignis to be dismembered by the monster's jaws. This made Varis and the Knights of Hanoi spend the following years searching for that Ignis' parts in order to find the location of Cyberse.
The Ignis that escaped was pursued relentlessly by the Knights of Hanoi. SOL Technologies later found out that the Ignis was roaming around LINK VRAINS, and had their security chief, Akira Zaizen, be in charge of the operation to capture it. The escaped Ignis was eventually caught by Yusaku Fujiki, who planned to use it as a weapon against the Knights of Hanoi.  Throughout the season, Yusaku operated covertly in LINK VRAINS as Playmaker, dueling against opponents that were affiliated with either SOL Technologies or the Knights of Hanoi.
- Playmaker defeated a Knight of Hanoi in his first Speed Duel.  He later called the captured Ignis "Ai".
- The Gore drew out Playmaker after agreeing to do so for SOL Technologies; he entered LINK VRAINS disguised as a Knight of Hanoi, and was tasked with capturing Playmaker's Ignis.
- Blue Angel challenged Playmaker out of a desire to prove her independence to her brother. But, while still waiting for Playmaker to respond to her challenge request, Blue Angel was visited by the Knights of Hanoi's second-in-command, Specter, who threw a card at her and left. Ai then detected a Knight of Hanoi inside LINK VRAINS, prompting Yusaku to log in and accept Blue Angel's challenge.  During the duel, Blue Angel played the card that was given to her, and her behavior changed to the point where she screamed in anguish and lost consciousness before the end of the duel. 
- With Specter's mission deemed a success, Varis headed to the location where Blue Angel was resting, in order to challenge Playmaker. Playmaker had been lured to that location by Ghost Gal, who agreed to do so for SOL Technologies by going into LINK VRAINS initially disguised as Blue Angel. After being lured, Playmaker was subject to torture by Akira Zaizen.
- Playmaker defeated Varis to obtain the cure to heal Skye.  After that, Akira was demoted, and SOL Technologies' stance shifted from pursuing the Ignis to protecting LINK VRAINS from the Knights of Hanoi. 
SOL Technologies' pursuit of the Ignis resumed with Akira Zaizen in charge of the operation under new boss Queen. Akira assembled a squad of bounty hunters: The Gore, Kenmochi, Yoroizaka and The Shepherd.  Their plans were put into disarray upon the Ignis' declaration of war on humanity.  Although SOL were successful in capturing one of the Ignis, Earth, he was forcibly terminated by Queen, an action that Akira did not approve of.  Following this, the only bounty hunter remaining, Shepherd, quit the squad.  SOL Technologies and the Knights of Hanoi then worked independently of each other to stop Lightning's faction and end the Ignis war.
- ↑ Yu-Gi-Oh! VRAINS episode 1: "Link into the VRAINS"
- ↑ Yu-Gi-Oh! VRAINS episode 2: "Seize the Wind!"
- ↑ Yu-Gi-Oh! VRAINS episode 3: "Contact"
- ↑ Yu-Gi-Oh! VRAINS episode 4: "Pain and Gain"
- ↑ Yu-Gi-Oh! VRAINS episode 6: "True Blue"
- ↑ Yu-Gi-Oh! VRAINS episode 7: "Fallen Angel"
- ↑ Yu-Gi-Oh! VRAINS episode 8: "A Storm is Coming"
- ↑ Yu-Gi-Oh! VRAINS episode 12: "Link the Circuit"
- ↑ Yu-Gi-Oh! VRAINS episode 14: "An Invitation"
- ↑ Yu-Gi-Oh! VRAINS episode 50: "A Common Cause"
- ↑ Yu-Gi-Oh! VRAINS episode 71: "A Logical Decision"
- ↑ Yu-Gi-Oh! VRAINS episode 75: "Earthfall"
- ↑ Yu-Gi-Oh! VRAINS episode 78: "From One Hunter To Another"