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Icon-build.png This article is about a/an villain in Kamen Rider Build.

"I am number one."
―Keiji's proclamation to Misora and Kazumi.

"Heroes? They are just mere fantasies."
―Keiji mocks Misora's ideals.[src]

"There is no such thing as being fair or dirty in war. Only the victor is justice. I thought you already had a taste of that back in the old world."
―Keiji's justification for his actions.

"With the White Panel, there's no way I would lose to someone that gets stronger from mere bonds like you."
―Keiji mocks Kazumi.

"It was for certain that I'm better than you in terms of power, but...why? What's the difference?"
―Keiji's last words.

Keiji Uraga (浦賀啓示 Uraga Keiji) is the main antagonist of Build NEW WORLD: Kamen Rider Grease who is able to transform into Kamen Rider Metal Build (仮面ライダーメタルビルド Kamen Raidā Metaru Birudo). He becomes the new leader of the terrorist organization Down Fall after killing Simon Marcus.


Keiji was a scientist who teamed up with Shinobu until his demise as the Zebra Lost Smash, like many of the previous Smash experimentation victims. During the Killbus incident, his memory returned along with his old wounds that happened with other previous victims in the New World. After Keiji remembered the incident of the previous world, he took his goal which he couldn't accomplish before, becoming the "ruler of the world" by creating a terrorist organization and hid his leadership by using Simon Marcus as the fake leader of Down Fall.

Keiji ambushed the Prime Minister building during Taizan, Shinobu, and Gentoku's introduction to Simon Marcus about their invention to protect the city, the Build Driver. During the ambush, Keiji had changed the group into Phantom Crushers with the newly discovered Phantom Liquid and prepared a bottle made of Nebula Gas to extract the Hazard Levels of the Riders and prevent them from transgorming, with Gentoku as the first victim followed by Sento and Banjou. After Keiji obtained the Build Driver and the Hazard Trigger, he killed Simon as he no longer needed him. Then, he obtained information that the Hokuto Sanbagarasu and Grease were still able to transform because their Hazard Level couldn't be absorbed, as Kazumi and his friends had unknowingly took a bath in a pool of Phantom Liquid. Keiji was interested in this and faced the Sanbagarasu where he targeted Misora, not knowing that Misora no longer has Vernage within her. By becoming Metal Build, he easily defeated the Sanbagarasu alongside Grease despite his late arrival and took Misora with her, not before he told Kazumi to bring him the White Pandora Panel.

Later, he had Kazumi come with the White Panel and faced Kazumi's Grease Blizzard and was defeated, but Keiji called a Phantom Crusher to attack Grease from the back and taking the White Panel. He absobed the White Panel and a Phantom Crusher that was nearby to become Phantom Build. As Phantom Build, Keiji gained an upper hand, even when Kazumi later gained the power-up from Ryuga to become Grease Perfect Kingdom, regardless how Kazumi felt pity on him for what happened in the previous world, feeling alone.

During the last moments of their fight, Keiji underestimated Kazumi's determination by mocking him as a weakling who relies on the others, which angered Kazumi to the point of raising his Hazard Level and made him able to use the true potential of Perfect Kingdom. With the complete defeat from Kazumi's Perfect Kingdom Finish, Keiji mourned by asking how Kazumi got stronger, which Kazumi replying that Keiji had nothing to fight for, much to his dismay as he died, with his body disappearing.

Video Game Appearances

Kamen Rider Buttobasoul

Phantom Build Buttobasoul.jpg

Phantom Build is a playable character in Kamen Rider Buttobasoul.


Keiji Uraga is a power hungry man and will use any method to achieve his goals, much like any higher ups of Faust during the previous world. For example, he coldheartedly shoots Simon Marcus to death when he reveals to betray him and take over as the leader of Down Fall.

He is very sensitive to be called either number two or being inferior to the one he faced as it would drive him mad, albeit he didn't show his anger brightly. Upon utilizing his plans, Keiji is calm and cautious, and whenever his plans worked splendidly, he would smirk in satisfaction before he reaches his final goals.

When his plans didn't work, however, he loses his cool to a degree, going as far to kill the Down Fall member who brought him the fake Last White Pandora Panel.

Other negative traits include being extremely arrogant, openly doubting the ideals of his enemies. He told Misora that heroes are just mere fantasies, and even mocks Kazumi's bonds with his comrades. This worsens when he merges with the Last White Pandora Panel to become Phantom Build, along with increased aggression as well.

All of this proves to be Keiji's fatal flaw, with him being defeated by Grease Perfect in the end. Even when he was vanishing, he still doesn't understand why he lost against him.


  • Hazard Level: Because of how extreme Lost Smash experimentation is compared to regular experimentation, Keiji has developed a high Hazard level, allowing him to utilize a Build Driver and bear the power of the Hazard Trigger.


  • Superiority Complex: Much like any higher up villains and Blood Tribes, Keiji has a superiority complex and is shown to be completely annoyed to be called number two. He can also be extremely arrogant, and even aggressive when someone mocks him or doubts his ideals, as shown when he was talking with Misora, and during his fight against Grease Blizzard, which the latter got punched heavily on the floor several times and got thrown out of a building through the wall in return.
  • Hazard Trigger: Although the two identical Fullbottles don't make him lose his consciousness and make him go berserk, the Hazard Trigger has the side effect onto Keiji despite it can grant him great strength. Like the Hazard Smash, Keiji can die permanently upon defeat.


Kamen Rider Metal Build

Kamen Rider Metal Build

"Tank! Tank! Are you ready? (Techno rock music) Uncontrol switch! Black Hazard! Yabei!"
―Transformation announcement[src]

Rider Statistics:[1]

  • Rider Height: 197.5 cm
  • Rider Weight: 101 kg

Ability Parameters:[1]

  • Punching Power: 49.1 t
  • Kicking Power: 55.3 t
  • Maximum Jump Height: 63.3 m
  • Maximum Running Speed: 100 m per 1.2 seconds

Keiji transforms into Kamen Rider Metal Build (仮面ライダーメタルビルド Kamen Raidā Metaru Birudo) by using the Metal TankTank Fullbottles in the Build Driver with the Hazard Trigger attached. Due to using two abiotic Fullbottles, Metal Build is incredibly durable and much more powerful than Build's normal forms. Keiji doesn't go berserk in this form, as he uses two identical Fullbottles in the same fashion as the FullFull RabbitTank Bottle.

  • Build Driver finishers:
    • Hazard Attack (ハザードアタック Hazādo Atakku): Metal Build jumps into the air before crashing into the target with a double knee drop. He then creates an energy tank tread that grinds the enemy into the ground.
    • Hazard Finish (ハザードフィニッシュ Hazādo Finisshu): Metal Build performs a roundhouse kick motion towards the opponent, creating a tank track that flies into the target and grinds against them, acting like a chainsaw. This attack can strike multiple opponents.

This form is exclusive to Build NEW WORLD: Kamen Rider Grease

Phantom Build

Phantom Build

Rider Statistics:[1]

  • Rider Height: 197.5 cm
  • Rider Weight: 121.9 kg

Ability Parameters:[1]

  • Punching Power: 57.8 t
  • Kicking Power: 63.4 t
  • Maximum Jump Height: 70.5 m
  • Maximum Running Speed: 100 m per 1 second

Upon merging with the white Last Pandora Panel, Kamen Rider Metal Build combines with a Phantom Crusher to form Phantom Build (ファントムビルド Fantomu Birudo). In contrast to the durability of Metal Build's normal form, Phantom Build demonstrates extraordinary speed.

This form's finisher is the Hazard Finish (ハザードフィニッシュ Hazādo Finisshu): Phantom Build launches a volley of missiles from his back before performing two consecutive roundhouse kicks towards the opponent, creating a tank track that flies into the target.

This form is exclusive to Build NEW WORLD: Kamen Rider Grease

Zebra Lost Smash

Zebra Lost Smash

The Zebra Lost Smash (ゼブラロストスマッシュ Zebura Rosuto Sumasshu) uses hooves on the end of his hands to fight and can create black-and-white shock waves with them. Before joining Down Fall, Keiji was forced to become the Zebra Lost Smash for experimentation.

This form is exclusive to Build NEW WORLD: Kamen Rider Grease




Behind the Scenes


Keiji Uraga is portrayed by Tamiyasu Cho (趙珉和 Cho Tamiyasu). As Kamen Rider Metal Build and Phantom Build, he is portrayed by suit actor Kosuke Asai (浅井 宏輔 Asai Kōsuke).

Concept Art

Zebra Lost Smash concept art

Zebra Lost Smash was designed by Tamotsu Shinohara (篠原 保 Shinohara Tamotsu).


  • Metal Build's suit is a direct reuse of Kamen Rider Build Hazard Form with two black tank visors.
  • Metal Build is the second Rider from Build to have a completely Abiotic motif, with the being first being Grease.
  • His backstory is similar to Yui Mabuchi in the previous Build NEW WORLD: Kamen Rider Cross-Z film.
    • Both were forcibly mutated into Hazard Smash, which would be used by the Blood Tribe members to transform into, and later burned to death following after.
    • Both received burn scars as a result of their deaths, which would be carried into Sento's recreated New World.


See Also


  1. 1.0 1.1 1.2 1.3 [1]
Icon-build.png Kamen Rider Build
Kamen Riders
Sento Kiryu (Takumi Katsuragi) - Ryuga Banjo - Kazumi Sawatari - Gentoku Himuro - Evolto - Nariaki Utsumi - Shinobu Katsuragi
Movie-exclusive: Kengo Ino - Killbus - Keiji Uraga
Drivers/Transformation Gear
Build Driver - Transteam Gun - Nebulasteam Gun - Sclash Driver - Evol-Driver
Transformation Devices
Fullbottles - (Great) Cross-Z Dragon - Sclashjellies - Hazard Trigger - Cross-Z Magma Knuckle - Evol-Trigger - Grease Blizzard Knuckle - Killbuspider - Grease Perfect Kingdom
Drill Crusher - Hawk Gatlinger - 4Koma Ninpoutou - Kaizoku Hassyar - Fullbottle Buster - Steam Blade - Beat Closer - Twin Breaker - Muscle Glove - Solstall Wings - Giant Scratcher - Space Ride Arm - Spine Knuckle - Long Range Cleaner - Trash Converter - Gold Lio Gauntlet - Multi Deluge Gun
Pandora Box - Halfbodies - Fullbottle Holder - Build Phone
Vortex Finish - Hazard Level - Project Build - Sky Wall - Nebula Gas
nascita: Misora Isurugi - Soichi Isurugi - Sawa Takigawa - Kazumi Sawatari - Gentoku Himuro
Kamen Riders: Eiji Hino - Gentaro Kisaragi - Kouta Kazuraba - Takeru Tenkuji - Emu Hojo - Hiiro Kagami - Taiga Hanaya - Kiriya Kujo - Kuroto Dan - Parado - Sougo Tokiwa - Geiz Myokoin - Tsukuyomi
Prime Ministers: Taizan Himuro (Touto) - Yoshiko Tajimi (Hokuto) - Masakuni Mido (Seito)
Namba Heavy Industries Ltd.: Juzaburo Namba - Nariaki Utsumi - Haruhiko Wanibuchi - Guardian
Hell Bro's: Fu Washio - Rai Washio - Yoshikazu Takahashi - Norio Matsui
Aliens: Vernage
Gentoku Himuro - Evolto - Nariaki Utsumi - Takumi Katsuragi - Shingo Kuwata - Eita Kawai - Yoshikazu Takahashi - Norio Matsui
Normal Smash: Fang Smash - Needle Smash - Strong Smash - Burn Smash - Flying Smash - Mirage Smash - Square Smash - Press Smash - Ice Smash - Stretch Smash
Empowered Smash: Strong Smash Hazard - Press Smash Hazard - Stretch Smash Hazard - Flying Smash Hazard
Hard/Hazard Smash: Castle Hard/Hazard Smash - Stag Hard/Hazard Smash - Owl Hard/Hazard Smash
Clone Smash: Press Clone Smash - Stretch Clone Smash - Strong Clone Smash - Flying Clone Smash
Lost Smash: Owl Lost Smash - Stag Lost Smash - Castle Lost Smash - CD Lost Smash - Scissors Lost Smash - Zebra Lost Smash
Foundation X
Kaisers: Kaisei Mogami (World of Build, World of Ex-Aid) - Nebula Bugster
Blood Tribe
Kengo Ino - Ryoka Saiga - Mitsuomi Gobara - Evolto - Killbus - Akaba (imitation) - Aoba (imitation) - Kiba (imitation) - Remocon Bro's (imitation) - Engine Bro's (imitation)
Down Fall
Keiji Uraga - Simon Marcus (Phantom Crusher)