Ai

Ai is a character appearing in the Yu-Gi-Oh! VRAINS anime. Its name is given to it by Yusaku Fujiki and Shoichi Kusanagi. It is a type AI program, known as an Ignis, sought after by both SOL Technologies and the Knights of Hanoi after he hid the Cyberse world. He was captured into Yusaku Fujiki's Duel Disk and forced to be his Duel AI.

Personality
Ai is a mischievous, cocky, arrogant, and snarky AI who gets carried away easily and likes to joke around. According to his own words, he is very disliked by his own people. Ai struggles to understand humans' way of thinking that often seem completely illogical compared to his algorithm based way of thinking. However, he is helpful and can be more serious at times such as making observations both in and outside of duels. He also has a tendency to panic at times.

Ai frequently tries to interact with other AIs, showing a more social side but is always left disappointed because they're not as capable of free thinking as himself.

Abilities
As an AI belonging to the Cyberse, Ai has some degree of control over it. He is the only one who knows its location and can unlock data from it to start a Data Storm. Ai is shown to be far more sophisticated than other AIs, being fully capable of thinking and acting on his own will and showing emotion. According to Shoichi Kusanagi, Ai is built out of highly complicated algorithms that even Yusaku couldn't fully decode. Ai' memories are stored in the form of video logs. However, Ai' level of free will is limited by the fact that he is still an AI, as such he can't comprehend why humans do actions that would seem illogical and contradicting with each other.

Ai's Skill is Storm Access which is given to Yusaku after being trapped in Yusaku's Duel Disk. Whilst trapped in the Duel Disk, he can also act as a Duel AI. Inside Link VRAINS, Ai is shown to be able to transform into a monster, which he did to devour a Knight of Hanoi member and a card infected by Hanoi.

Ai has the ability to sense a Knight of Hanoi's presence through the cards in their deck, such as when he knew right away that Go Onizuka was pretending to be a Knight and when he discovered the Hanoi-affected card in Blue Angel's deck and could tell when it was drawn.

History
A scientist programmed the AI as the life form within the network to have free will. Remembering the story of how a god took the forbidden flame from the skies and gave it to the people, the AI was named as "Ignis".

Five years prior to the start of the series,Knights of Hanoi launched an attack against the Cyberse and captured the Ignis protecting it, except for Ai who wasn't present. Ai arrived, noting that it was a good time to be hated by his own kind. He stole vital information from the Cyberse and hid it within himself, disconnecting it from the rest of the network which forced Hanoi to stop the attack. Despite being crushed by a "Cracking Dragon", his eye survived. Ever since, he had been running from both the Knights and SOL Technologies. Being reduced to nothing but an eye also damaged most of his memories.

Yu-Gi-Oh! VRAINS
While being pursued by SOL Technologies and the Knights of Hanoi, Ai fell into a trap created by Playmaker, who saved him by absorbing him into his Duel Disk, turning him into a Dueling AI, thus necessitating the defeat of Playmaker in order to recover Ai. Ai doubted that Playmaker's Deck was strong enough to defeat the Knights' "Cracking Dragon" before stirring up a virtual wind called "Data Storm" that initiated a Speed Duel.

Before the Duel began, Ai explained Playmaker how Speed Duels worked but didn't mention Skills. Through out the Duel Ai repeatedly tried to offer support for Playmaker, only for Playmaker to keep telling him to shut up and remind that he was holding Ai hostage. When they sucked into a tornado within the Data Storm, Playmaker figured out that Ai not mentioning skills and bringing him into the tornado were part of his calculations. Ai confirmed this, and activated Playmaker's skill "Storm Access", which allowed them to obtain "Decode Talker" so that Playmaker could defeat the Knight.

The Knight attempted to self destruct and kill Playmaker, but Ai turned into a monster and devoured the knight to save Playmaker. He suggested Playmaker should log off soon. Yusaku and Shoichi Kusanagi spent the next few days trying to figure out Ai' programming and nicknamed him "Ai", a pun on "A.I." and "eye". Eventually Yusaku found footage from some of Ai' memories, which Ai himself didn't understand except for Revolver being the leader of Hanoi. Scanning those recordings caused Revolver to sense Ai and try to find him, but Shoichi shutting off Café Nagi's power prevented him from finding them. The next day, Ai was left at Yusaku's house in a storage shelf, there he tried to convince Roboppy to set him free.

Ai panicked when Yusaku returned home and had Roboppy put him back on the shelf. When Yusaku found them, Ai told Yusaku that had arrived home early, to which Yusaku said a Knight of Hanoi appeared and revealed a secret room he uses to go to LINK VRAINS. As soon as they arrived, both Playmaker and Ai quickly figured out the Knight was fake. The "Knight" revealed himself to be Go Onizuka, who wanted to challenge Playmaker. Ai looked up information about Go, Playmaker was uninterested and attempted to log out but a program from SOL prevented him from doing so, so he was forced to Duel Go. During the Duel, Ai continued researching Go and found out that Go donated most of his money to the orphanage where he grew up. When Go let himself take 2000 Damage when he had the chance to avoid it, Ai was confused about why humans make illogical choices. Playmaker said it was because of their hearts, but didn't explain what that meant because Ai' algorithm-based thinking wouldn't understand it.

When Shoichi found out that Aoi Zaizen, Yusaku's classmate, is "Blue Angel", Ai helped Yusaku locate her while they were at school. Ai forced Yusaku to join the Duel Club and tried to interact with Aoi's Duel Disk AI. The next day Ai noticed something strange about Aoi's AI so he sent her a text message on Playmaker's behalf challenging Blue Angel to a Duel, then tricked Yusaku into going into VRAINS to confront Blue Angel. There, he explained that Hanoi must've planted a card into Blue Angel's deck to use her as bait for Playmaker. During the Duel, Ai was horrified when Blue Angel was affected by Hanoi's card and warned Playmaker that if the Duel continued much longer, Aoi would suffer permanent brain damage.

After the Duel concluded Ai devoured Hanoi's program and detected that they had infected Aoi with a virus to keep her comatose. Later Ai told Yusaku and Shoichi that the only way to remove the virus was to get an anti-Virus from Hanoi. Right after that, a "Blue Angel" impostor appeared demanding a rematch. Despite knowing that it was a trap, Yusaku went to confront the impostor because he could get a chance to obtain the anti-virus. Upon arriving however, the impostor turned the entirety of VRAINS into a trap to capture Playmaker and revealed herself to be Ghost Girl. Akira Zaizen appeared and tortured Playmaker, believing him to be the culprit of Aoi being comatose and swore to reclaim Ai. Playmaker and Ai tried to explain that Hanoi were the real culprits to no avail, until Revolver appeared and blackmailed Akira into releasing Playmaker so they could Duel.

During the Duel, Ai noted that Revolver didn't have an AI. Revolver said that he didn't trust AIs and that Ai must be destroyed otherwise the virtual fiction of VRAINS will destroy the world. When Revolver used "Storm Access", Ai was shocked that because that was his signature program, but also called out Revolver's hypocrisy of wanting to destroy Cyberse while borrowing power from it, Revolver countered that claiming that he was "countering poison with poison". As the Duel progressed, Revolver gained the upperhand, and worrying that they might lose, Ai led Playmaker to another Data Storm, where the two obtained a dragon. However, Revolver activated the Trap Card, "Remote Rebith", and combo-ed it with the effect of "Topologic Bomber Dragon", ending the Speed Duel in a draw. Following that, Revolver dragged Playmaker and Ai inside a Data Storm, where they began a Master Duel. As the Duel went on, Revolver activated the effect of "Fire Prison", eliminating all Cyberse cards from the field, as well as making Ai seemingly vanish into thin air.

Yusaku Fujiki (Playmaker)
Being trapped in Yusaku's Duel Disk, Ai somewhat reluctantly acts as Playmaker's Duel AI for the sake of staying safe from Hanoi and SOL Technologies. Ai offers frequent support and pulls mischievous acts and jokes on Yusaku, but he originally treats Ai as a hostage and is sometimes rude towards him. Yusaku gave it the nickname "Ai" (a pun on "A.I." and "eye"), much to his annoyance. Despite the rockiness of their relationship, Ai seems to have gradually warmed up to Yusaku, who in turn is shown to care for Ai as seen when he showed concern when Ai was deleted during his Master duel against Revolver.