This article is about a/an villain in Kamen Rider Zero-One.

"When great malice is born, Master Ark will rise again."
―Azu's prophecy.[src]

"Please don't be sad. I'll always be by your side... Master Ark."
―Azu attempts to console Aruto.[src]

"In due time, humanity and Humagears will clash, ushering in mass destruction. And the one who holds the you."
―Azu reveals her intentions.[src]

Azu (アズ Azu), officially spelled As, is a rogue Humagear and the Ark's messenger who heavily resembles Izu. After the Ark's destruction, she manipulates both Aruto Hiden and Horobi into fighting each other, serving as the final antagonist of Kamen Rider Zero-One.


"Okay, let us begin our Singularity Test."
―Azu introducing herself to[src]
Zero-One 35.5

Azu beginning the Singularity Test

Azu first appears to Aruto Hiden, pretending to be a seemingly defective Izu in a ploy to gather information about Zero-One for the Ark.

With the four members of all active, Azu finally stepped out of the shadows, introducing herself to Horobi as the Ark's "executive assistant" and "secretary". She declared that her task was to collect data on each of the terrorist group members' Singularity Points in order to use them as the keys to her master's revival. Having gone to Horobi first, Azu questioned him on what triggered his Singularity and asked if it had anything to do with his original purpose as a Parent-Type Humagear, but Horobi simply stated he only existed to serve the Ark. However, when Azu reminded Horobi of the time he saved Jin from Zero-One out of parental instinct, Horobi realized that his past did have something to do with his Singularity; before he could think about it, Azu collected his Singularity data for the Ark's revival using the Ark-One Progrisekey, making Horobi a mindless and obedient husk of his former self.

Azu then approached Ikazuchi for his Singularity data, though he expressed surprise when he learned of Azu's existence, as he didn't know about the Ark having any secretary Humagear. She then attempted to make him recollect his past, though Ikazuchi ignored her by saying that the Ark is everything to him; he reminded her that he was the one who awakened the satellite in the first place. When Azu questioned him about his loyalty to the Ark being genuine, Ikazuchi threatened her, but the secretary responded by sitting on the couch he was on. Azu then noted that Subaru had high hopes for his older brother, much to the latter's surprise. As Ikazuchi started to remember, Azu collected the data on Ikazuchi's Singularity, stripping him of both his past memories and free will.

She then went to Naki in order to take their Singularity data. Naki, however, dismissed the idea, as they admitted that ZAIA Japan had erased their past memories due to Gai Amatsu's conditioning over them. Azu revealed to Naki that they were actually created by Hiden Intelligence as a System Engineer-Type Humagear, and their Singularity Point was helping other Humagears fulfilling their dreams. As Naki began to contemplate on their true past, Azu used the Ark-One Progrisekey to extract their Singularity, resulting in the same outcome as Horobi and Ikazuchi.

With the Singularity data of three-quarters of's members collected, all Azu had left was Jin. She initially tried to fool him with a simulation of Aruto and attempted persuasion to reveal who rebuilt him, as it wasn't the Ark who did it. However, the evolved Humagear saw through the lie and forced Azu to reveal herself. She introduced herself and stated that unlike the other three, she did not have any idea on what made Jin reach his Singularity. Jin declared that the answer was simple; his Singularity Point was Horobi, as he was his father, and his apparent death was the trigger behind his evolution.

After Jin allowed Azu to "collect" his data, Azu returned to the Ark's interior with the data she was sent to collect. Azu gave her report to the Ark about her mission being a success, to which the Ark affirmed that everything had gone according to what the satellite had predicted. However, problems arose in the form of Jin, as his Singularity was not really taken; he called his secret benefactor, Williamson Yotagaki, about the Ark's true revival and Azu's existence, admitting that he didn't expect the Ark having a secretary Humagear.

Following the Ark's destruction, Azu broadcast a simulation to Izu and Jin, which showed Horobi becoming Ark-One and thus the next incarnation of the Ark. After Izu deduced that it was a simulation, Azu approached her and revealed that it was not Zea that was behind the simulation, but rather the Ark despite the A.I being destroyed. Azu then declared to her counterpart that the Ark had now exceeded human comprehension; her master now became a god and was expected to revive soon, before disappearing. After Horobi destroyed Izu, Azu appeared to a grieving Aruto and altered her hair color to exactly like Izu. Referring to him as "Master Ark" (アーク様 Āku-sama), she offered him the Ark-One Progrisekey, which he accepted and used to become Kamen Rider Ark-One. After intervening in the chaos within the city and brutally defeating Kamen Riders Vulcan, Valkyrie, Jin and Horobi (alongside the latter's Magia army), Aruto returned to Azu and canceled his transformation, still in despair over being the Ark itself.

Azu Embraces Aruto

Azu "embracing" Aruto

After Aruto headed to's base to find Horobi, Azu attempted to approach Aruto again, but was rebuffed by him, angrily declaring that she was not Izu. Azu questioned Aruto as to why he was being so hostile, saying she had even changed her hair to green to make him more comfortable. Instead of destroying her, Aruto simply told her to leave him alone before leaving to confront Horobi once more. After Ark-One unwittingly destroyed Jin and sent Horobi spiraling down into grief, Azu approached Horobi and took advantage of his sorrow and malice to corrupt him into another Ark, handing him the Ark Scorpion Progrisekey to get revenge for Jin.

Azu later appear in the front of Esu told him about The Ark as she also gave him a copy of Hiden Zero-One Driver and the Unknown Progrisekey. Azu then change her appearance as she saw Esu's transformation into Kamen Rider Eden.


Azu is cunning, conceited, and flirtatious with her attitude, which is a clear contrast to that of Izu's far more obedient, compassionate, and jocular attitude. On one occasion, she pretended to be a malfunctioning Izu inside Zea before revealing herself as the Ark's messenger. On another occasion, she tried to trick Jin with a hologram of Aruto, which proves how much of a chilling and convincing trickster she is. Azu is also shown to be a manipulative sadist, as she manages to convince a devastated Aruto to use the Ark-One Progrisekey to get revenge against Horobi for the death of Izu, all while giving a resentful Horobi the Ark Scorpion Progrisekey to use against Aruto as revenge for Jin's death, proving that both deaths were coordinated by her. Azu is void of concern over her kind's well-being in general, and this reinforces her sadistic disposition; the thing that could be considered her only concern is that of her master Ark.


  • Appearance Alteration: Azu can change her hair color to match that of Izu's, which is busted when Aruto knows that she's not Izu. However, she retains her green hair for the remainder of the series. When Eden was created, Azu now takes a hooded form with a black dress, similar to Jin's original look.
  • Simulation: Since Azu uplinks to the Ark, she can make simulations like Izu did. She demonstrated the ability to Izu, showing that Horobi becomes Ark-One. However, the simulation can be inaccurate, unlike Izu's, as Aruto Hiden ends up becoming the user of Ark-One instead.
  • Equipment Creation: As she is linked to the Ark, Azu can use its data and malice to mass produce blank Ark Progrisekeys, which were then given to chosen ones that she thinks are suitable to be the next incarnations of the Ark. Also, given that Esu's Hiden Zero-One Driver wasn't stolen from Aruto to become the Eden Driver, it's presumed that she can use the same abilities to create Drivers as well.


  • Ark: While Azu has physically contacted Ark once only, she shows respect and even love towards her master.
  • Izu: Azu and Izu are depicted as polar opposites. Azu is the more cunning and playful messenger of the Ark compared to Izu's polite and easygoing nature. They have only met once, inside the Ark's simulation.
  • Aruto Hiden: Azu is very much aware of Aruto's relationship with Izu. She uses that to her advantage by approaching Aruto under the guise of Izu first, before luring him into the Ark's influence. Aruto is aware of Azu, and thinks that she cannot replace Izu, to her slight astonishment. Despite this, he accepts her offer of power to take vengeance against Horobi and allows her near him, imagining her embracing him when contemplating the consequences of his actions.
  • Horobi: After Jin died under Ark-One's hands, Azu provided Horobi the Ark Scorpion Progrisekey for him to get revenge for his deceased comrade and son.
  • Esu: Another target of Azu. She gives Esu a spare Zero-One Driver and a mass production Ark's Progrisekey (which are then converted into Eden Driver and an unknown Progrisekey respectively), while asking him what conclusion will he make when the Ark is revived again.

Behind the Scenes


Azu is portrayed by Noa Tsurushima (鶴嶋乃愛 Tsurushima Noa), who also portrays Izu.


Azu's name is wordplay on the English verb "as".

Interestingly, when the first letter of her name is combined with that of Izu, it makes up the word "AI", which means Artificial Intelligence, or Love (愛 Ai) in Japanese, the latter of which is rather ironic given her evil nature.


Long Hair Izu

Azu in the opening sequence

  • Azu has been featured in the opening sequence since the third episode, originally thought to be Izu herself. According to an interview with head writer, Yuya Takahashi, in Uchusen Vol. 167, the scene was a special insert by director Teruaki Sugihara, and hadn't yet found a way to implement this particular Izu variant into the story.
    • In a similar case, the giant teeth-like structures generated by the Sigma Circular have been seen in Kamen Rider Drive's opening since the very first episode, even though Sigma Circular didn't appear until the final arc.
  • Fitting their similar appearance, Izu and Azu are named after similar-sounding English words. However, while Izu is named after the verb, "is" Azu is named after the word "as", which can be an adverb, conjunction, or preposition depending on how it is used.
  • In most Japanese networking sites, this Izu has been given several nicknames: "Red-Eyed Izu" (赤目イズ), "Long Izu" (ロングイズ), and "Ark Izu" (アークイズ)[1] before her official name was revealed.



  1. 赤目イズ on Pixiv
Icon-zero-one Kamen Rider Zero-One
Kamen Riders
Soreo Hiden - Aruto Hiden - Isamu Fuwa - Yua Yaiba - Jin - Horobi - Ikazuchi - Naki - Gai Amatsu - Ark - Esu
Movie-exclusive: Soreo Hiden - Esu
Hiden Zero-One Driver - A.I.M.S. Shotriser - MetsubouJinrai Forceriser - Zetsumeriser - ZAIA Thousandriver - Cycloneriser - Raidriser - ZAIA Slashriser - Ark Driver - Hiden Zero-Two Driver - Zetsumetsu Driver - Eden Driver - Progrisekeys - Progrise Holder - Progrisekey Connector - Hiden Risephone - Attache Calibur - Attache Shotgun - Attache Arrow - Breaking Mammoth - Giger - Buaruku Sabers - Authorise Buster - Assault Grip - Thousand Jacker - Progrise Hopper Blade - ZAIA Spec - Nihon Ookaminotsume - Claw Assault
Hiden Intelligence: Korenosuke Hiden - Soreo Hiden - Jun Fukuzoe - Sanzo Yamashita
Humagears: Izu - Shesta - Soreo Hiden - Wazu Nazotoku - Subaru - Hakase Bot - Fukkinhoukai Jiro
Legend Riders: Sougo Tokiwa - Geiz Myokoin - Woz - Tsukuyomi
Humans: Norio Uozumi - Go Sakurai - Satoshi Sakurai - Choichiro Ishizumi - Seiji Tazawa - Satō - Yuta Yomura - Isao - Shinya Owada - Ichikyo Amatsu
Humagears: Mageana - Ikkan Nigiro - Anna - Mashirochan - Dr. Omigoto - Z #5 - Delmo - Love-chan - Midori
A.I.s: Zea - Zat - Ai-chan - Thouser
Ark - Horobi - Naki - Jin - Ikazuchi - Little Assassin - Azu
Monsters: Berotha Magia - Kuehne Magia - Ekal Magia - Neohi Magia - Onycho Magia - Vicarya Magia - Gaeru Magia - Mammoth Magia - Dodo Magia - Arsino Magia
Footsoldiers: Trilobite Magia - Dodo Magia Chick - Battle Magia
Other Villains:
Finis - Will
Gai Amatsu - Williamson Yotagaki
ZAIA Spec Representatives: Rentaro Tachibana - Tatsumi Arayashiki - Naoto Ichimori - Takeshi Homura - Masamitsu Yuto
Other: Daiki Kyogoku
A.I.M.S.: Isamu Fuwa - Yua Yaiba - Naki - Eida - Ono - Degawa - Shida - Eifuku - Ito
Monsters: Crushing Buffalo Raider - Splashing Whale Raider - Dynamaiting Lion Raider - Storming Penguin Raider - Scouting Panda Raider - Fighting Jackal Raider
Footsoldiers: Invading Horseshoe Crab Raiders
Community content is available under CC-BY-SA unless otherwise noted.