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Naki is a member of MetsubouJinrai.NET and a major antagonist in Kamen Rider Zero-One, serving as the secondary antagonist of the "Hiden Intelligence Vs. Zaia Enterprise" arc and a major antagonist in the "Hiden Manufacturing" arc.
Naki's AI was implanted in the head of A.I.M.S. Captain Isamu Fuwa by Gai Amatsu, granting Naki control of Fuwa's body. In Fuwa's body, Naki is the one who initially distributes the RaidRisers that allow people to turn into Raiders.
After being freed from Zaia Enterprise and transferred from Fuwa's head into a new body by Jin and Yua Yaiba, Naki rejoins MetsubouJinrai.NET and assists them in their goals of driving humans to extinction.
Naki is portrayed by Satsuki Nakayama.
Naki was one of four HumaGears hacked by the Ark after it went rogue and programmed to form MetsubouJinrai.NET to carry out its will of destroying humanity.
After the Daybreak Town Incident, which saw the total leveling of Daybreak Town, the four members of MetsubouJinrai.NET continued to operate in secret. While Ikazuchi acted as a sleeper agent within Hiden Intelligence and Horobi and Jin began preparations to program the ZetsumeRise Keys and reawaken the Ark, Naki took up an unknown role and was somehow able to obtain technology from Hiden Intelligence for MetsubouJinrai.NET to use. Naki at some point began working for Gai Amatsu, who reprogrammed Naki's AI to be loyal to him. Naki's AI was later stored inside of an AI chip planted in the mind of Isamu Fuwa.
After MetsubouJinrai.NET's seeming destruction and Horobi's capture by A.I.M.S., Naki emerged and somehow obtained the RaidRisers from Zaia Enterprise. Naki began providing the RaidRisers to humans involved with the Workplace Competition between Hiden Intelligence and Zaia Enterprise, granting them the power to become Raiders.
Naki's first target was Rentaro Tachibana, the contestant chosen to represent Zaia in the first round of the competition, who Naki forced to become Crushing Buffalo Raider. However, the Raider was defeated by Kamen Rider Thouser, freeing Rentaro from the RaidRiser's influence. Naki would go on to provide RaidRisers to Tatsumi Shinyashiki, Masuji Narusawa and Teruo Nikaido, who all willingly used them to become Raiders.
Later, Naki aided Jin in freeing Horobi from his imprisonment by A.I.M.S. by possessing A.I.M.S. captain Isamu Fuwa through the A.I. chip implanted in his brain and using him to break Horobi out. Naki and Jin also hacked the security camera footage to Horobi's room to cover up how they broke Horobi out. While Jin and Horobi returned to their base in the wreckage of Daybreak Town, Naki did not go with them.
Jin later attempted to free Naki from Fuwa's head, but was stopped by Horobi, who told him Fuwa being Naki's host was the will of the Ark.
After Fuwa defected from A.I.M.S. to become a guard at Aruto Hiden's new company, Hiden Manufacturing, Yua Yaiba was sent by Gai to reawaken Naki's AI in order to bring Fuwa back under ZAIA's control. During a skirmish between A.I.M.S. Battle Raiders and the Kamen Riders, Yua forcibly inserted the Assault Wolf key into Isamu's ShotRiser and forced him to become Kamen Rider Vulcan Assault Wolf, causing Naki to regain control. As Assault Wolf, Naki assisted the Horseshoe Crab Raiders in fighting Zero-One Metalcluster Hopper, but just as they were about to overwhelm him, Kamen Rider Jin Burning Falcon arrived and assisted Zero-One in fighting them off. Jin later took Fuwa's body to MetsubouJinrai.NET's base so he could break Gai's conditioning of Naki and extract them from Fuwa's head. Jin tried to get Naki to reach Singularity, but Naki repeatedly affirmed that they were nothing but a tool. Just as Jin was about to make a breakthrough, Isamu woke up and, not knowing what Jin was trying to do, stormed out to go to Delmo's runway event and provide security there.
However, while there, Isamu was confronted again by Jin and Horobi who were able to break Gai's control over Naki and help them develop independence. Fuwa/Naki later transformed into Kamen Rider Rampage Vulcan and assisted Kamen Rider Zero-One in driving off Thouser and the Raiders.
Yua Yaiba later kidnapped Fuwa and brought him to MetsubouJinrai.NET's base so they could work to extract Naki from him. While Horobi focused on retrieving Spaceman Raiden's data, Yua and Jin hooked Fuwa up to a device to retrieve Naki's memory from his head. Once Naki was freed and restored to a body, MetsubouJinrai.NET was able to, using the data Naki had collected as a member of ZAIA, hack into ZAIA's ZAIASpec network and mind control all of its users into going berserk and attacking other humans.
However, Fuwa then wakes up and tries to get Naki to stop, asking what the HumaGear's dream really is. Hesitating, Naki releases control of all of the ZAIASpecs and their users return to normal. Later, as Zero-One is fighting against Gai's Gigers, Naki appeared and hacked into ZAIA's systems, turning the Gigers and Battle Raiders against Gai.