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Icon-zero-one.png This article is about a 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 key...is you."
―Azu reveals her intentions.[src]

Azu (アズ, Azu), officially spelled As, was 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.


Singularity Test

"Okay, let us begin our Singularity Test."
―Azu introducing herself to MetsubouJinrai.net[src]

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 MetsubouJinrai.net 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. After approching Horobi, Naki, Ikazuchi, and Jin to collect their Singularity data, 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.

The Next Incarnation of Ark

Following the Ark's demise, 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's 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 her master, 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, Horobi, and the Magia army. Aruto returned to Azu still in despair over being the Ark itself.

Azu "embracing" Aruto

After Aruto headed to MetsubouJinrai.net's base to find Horobi, Azu approaches 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.

Right following the end of Aruto and Horobi's final battle, Azu later appears in the front of Rihito Isshiki, known as S, and told him about Ark as she also gave him a copy of Hiden Zero-One Driver and an incomplete Ark Progrisekey, which would turn into the Eden Zetsumerisekey. Azu then changes her appearance into a bridal gown as she saw Rihito's transformation into Kamen Rider Eden.

Other Events

Kamen Rider Zero-One: Final Stage

Azu transform into Ark-Zero-One

One day, Azu sensed the Ark's presense within her and transforms into Kamen Rider Ark-Zero-One. Immediately after the transformation, Azu's voice was a mixture of her own and Ark, which then became the Ark's voice itself. As Ark-Zero-One, she continues to have the advanced prediction and production capabilities like her master. Ultimately, Ark-Zero-One was defeated by Zero-Two and Azu is forced to withdraw, still believing as long as malice exists, the Ark will return.

Kamen Rider Zero-One: REAL×TIME

Three months after the war between him and Aruto ended, Azu continues to observe Rihito Isshiki (S) as he leads his followers at Thinknet to destroy the world and replace it with a "paradise". She remains in the background during the chaos, which caught Horobi's attention. Although he questions her objectives, Azu explains that this is part of the Ark's conclusion before leaving.

Zero-One Others

Azu's death

Following the defeat of Thinknet, Azu approached Lyon Arkland, CEO of ZAIA Enterprise's main branch, to be her new candidate for the next incarnation of Ark. She conspired with Arkland to kidnap Jin and mass-produce military-type Humagears called Solds. However, Lyon had no interest in becoming the next Ark and executed Azu shortly after making his true goals known. After her death, she was given a proper funeral by Jin and the other members of MetsubouJinrai.net.

Video Game appearances

Battle Spirits

Azu in Battle Spirits

Azu appears with other Kamen Riders and Monsters in Battle Spirits.


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. Even after Ark's death, she continues to be loyal to him and searches for anyone to become the host for Ark. Despite her attempts to manipulate others, Azu is repeatedly shown to be short-sighted in her schemes, such as when she attempted to corrupt Lyon Arkland into being the next Ark, even though he rejected malice in favor of justice, leading to her demise by his hand.


  • Appearance Alteration: Azu was able to materialize and wear different outfits with every single Ark successor she had followed:
    • Aruto Hiden: Azu's hair turned green to match Izu, who was Aruto's closest confidante in the series.
    • Horobi: Azu's hair turned red to show that she was no longer tethered to Aruto as an Izu lookalike.
    • S: Azu wore a black mourning dress to portray the fact that S had lost his fiance.
    • Lyon Arkland: Azu wore a black leather jacket with a red dress to show her rebelling with Lyon.
  • 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, though it is also likely that Azu deliberately showed her counterpart a false simulation in order to manipulate Aruto into becoming an incarnation of the Ark.
  • Equipment Creation: As she is linked to the Ark, Azu can use its data and malice to mass-produce blank Ark Progrisekeys, which are then given to chosen ones that she thinks are suitable to be the next incarnations of the Ark. As her plans over the course of the series involve several Hiden Zero-One Drivers of unknown origin, it is implied that this ability extends to the creation of drivers as well.
    • Rapid Adaptation: All equipment Azu creates through her abilities start out blank, but have the ability to change their appearance and function to match their user when coming into contact with a host. The first Zero-One Driver/Ark Progrisekey pair given to Horobi transformed into equipment based on his Rider form and his position as MetsubouJinrai's leader, while the second pair given to Rihito transformed into a Zetsumerisekey and driver unit based on humans, symbolizing his desire to wipe out humanity. Azu's own Zero-One Driver is unchanged, but has her Progrisekey become a variant of Ark-One, symbolizing the union between the Ark and Zea creating Ark Zero-One.


  • Ark: While Azu has physically contacted Ark once only, she shows respect and even love towards her master. After Ark's death she continue to be loyal towards him. Her loyalty towards Ark also lead to her death.
  • 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.
  • Rihito Isshiki: Another target of Azu. She gives Rihito a spare Zero-One Driver and a mass production Ark's Progrisekey (which are then converted into Eden Driver and the Eden Zetsumerisekey respectively), while asking him what conclusion will he make when the Ark is revived again.
  • Lyon Arkland: Arkland is the only person who declines Azu's offer and ultimately had his Solds assassinate her.


Kamen Rider Ark-Zero-One


"Progrise! Final Conclusion! Ark Rising Hopper! A jump to the sky to gain hatred."
―Transformation Announcement[src]

Rider Statistics

  • Rider Height:
  • Rider Weight:

Ability Parameters

  • Punching Power:
  • Kicking Power:
  • Maximum Jump Height:
  • Maximum Running Speed:

Azu transforms into Ark Zero-One (アークゼロワン, Āku Zerowan) by using the Ark-Zero-One Progrisekey into the Hiden Zero-One Driver.

This form's finisher is the Ark Rising Impact (アークライジングインパクト, Āku Raijingu Inpakuto).

This form is exclusive to Kamen Rider Zero-One: Final Stage.



  • Hiden Zero-One Driver - Main Transformation Device. (Exclusive to Kamen Rider Zero-One: Final Stage)
  • Progrisekeys - Transformation trinkets (Exclusive to Kamen Rider Zero-One: Final Stage)
  • Progrise Holder - Carrying straps for Progrisekeys (Exclusive to Kamen Rider Zero-One: Final Stage)

Behind the Scenes

Ark-Zero-One Concept Art


Azu is portrayed by Noa Tsurushima, who also portrays Izu. As Kamen Rider Ark-Zero-One, she is voiced/co-voiced by Show Hayami and was portrayed in-suit by an unidentified suit actor.


Azu's name is a play on the English word "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, though rather ironic given her evil nature, is related to her undying love, respect and loyalty towards the Ark.


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.
  • 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.
  • Kamen Rider Ark-Zero-One's suit is recolored from Kamen Rider Ark-One, with Kamen Rider Zero-One's boots and a modified version of Rising Hopper's transformation phrase.
  • Most of Azu's appearances and guises vary whenever she serves the Ark and his many incarnations:
    • Ark: Azu retains the identical Izu appearance with the long hair and red strands to represent her as the Ark's secretary similar to how Izu is to Aruto Hiden.
    • Aruto Hiden & Horobi: Azu simply changes her red strand into a green color to almost resemble Izu. This ties into Aruto's grief over Izu's death and Horobi's guilt for murdering Izu in the first place.
    • S: Azu wears a black wedding dress that symbolizes S's goal to reunite with his fiancée, Akane Tono, who he was supposed to marry before her untimely death during the Daybreak Town Accident.
    • Lyon Arkland: Azu sports a black leather jacket and a red fabric dress. She wears a professional and business-like attire as an analogous to Arkland's profession as the ZAIA Enterprise CEO.



  1. 赤目イズ on Pixiv
Icon-zero-one.png Kamen Rider Zero-One
Kamen Riders
Soreo Hiden - Aruto Hiden - Isamu Fuwa - Yua Yaiba - Jin - Horobi - Ikazuchi - Naki - Gai Amatsu - Ark - S
Movie-exclusive: Soreo Hiden - S - Behru - Kamen Rider Abaddon - Izu - Lyon Arkland - Kamen Rider MetsubouJinrai (Jin, Horobi, Ikazuchi & Naki)
Stageshow-exclusive: Azu - Little Assassin
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 - Abaddoriser - MetsubouJinrai Driver
Progrisekeys - Progrise Holder - Progrisekey Connector - Hiden Risephone - Rider Models
Attache Calibur - Attache Shotgun - Attache Arrow - Breaking Mammoth - Giger - Buaruku Sabers - Authorise Buster - Assault Grip - Thousand Jacker - Progrise Hopper Blade - ZAIA Spec - Knuckle Demolition - Nihon Ookaminotsume - Claw Assault - Horobi's Katana
Hiden Intelligence: Korenosuke Hiden - Soreo Hiden - Jun Fukuzoe - Sanzo Yamashita
Humagears: Izu - Shesta - Soreo Hiden - Wazu Nazotoku - Subaru - Hakase Bot - Fukkinhoukai Jiro - Rin
Legend Riders: Sougo Tokiwa - Geiz Myokoin - Woz - Tsukuyomi - Kuroto Dan - Masamune Dan
Humans: Norio Uozumi - Go Sakurai - Satoshi Sakurai - Choichiro Ishizumi - Seiji Tazawa - Satō - Yuta Yomura - Isao - Shinya Owada - Ikkei Amatsu - Akane Tono
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
ZAIA Japan
Gai Amatsu - Williamson Yotagaki
ZAIA Spec Representatives: Rentaro Tachibana - Tatsumi Arayashiki - Naoto Ichimori - Takeshi Homura - Masamitsu Yuto
Other: Daiki Kyogoku - Makio Nodachi
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
ZAIA Enterprise (U.S.A.)
Lyon Arkland - Sold9 - Sold20 - Sold404
Monsters: Dire Wolf Sold Magia - Serval Tiger Sold Magia - Crushing Buffalo Sold Magia - Splashing Whale Sold Magia - Storming Penguin Sold Magia - Scouting Panda Sold Magia - Invading Horseshoe Crab Sold Magia
Footsoldiers: Solds
S - Behru - Buga - Mua - Lugo
Footsoldiers: Kamen Rider Abaddon