This article is about a/an transformation equipment in Kamen Rider Build.
Hazard Trigger Opened

Hazard Trigger

"Hazard On! (Rock music)"
―Activation announcement[src]

"(Organic Fullbottle name)! (Inorganic Fullbottle name)! Super Best Match!"
―Super Best Match announcement[src]

"Don Ten Kan! Don Ten Kan!"
―Looping standby announcement[src]

"Gata Gata Gotton! Zuttan Zutan!"
―Vortex Crank cranking announcement[src]

"Uncontrol Switch! Black Hazard! Yabei!"
―Hazard Forms' transformation announcement[src]

"Ready, go! Hazard Attack!"
―Hazard Forms' charged attack announcement[1][src]

"Max Hazard On!"
―Overflow Mode activation announcement[src]

"Ready, go! Overflow! Yabei!"
―Overflow announcement without the Cross-Z Dragon, RabbitTank Sparkling Fullbottle, or FullFull RabbitTank Bottle[src]

"Ready, go! Hazard Finish!"
―Hazard Forms' finisher announcement[src]

The Hazard Trigger (ハザード トリガー Hazādo Torigā) is a turbocharger-like device that allows Kamen Rider Build to upgrade each Best Match into a Super Best Match (スーパベストマッチ Supā Besuto Matchi).


The Hazard Trigger is composed of the following parts:

  • The Force Ride Meter (フォースライドメーター Fōsu Raido Mētā) is located at the centre of the Hazard Trigger. It measures the fighting ability of the user, and the higher the reading, the more powerful the attacks are. However, if the meter reaches the dangerous zone during battle, the user will go beserk due to massive amounts of stimuli, causing a loss of sense of self.
  • The Progress Tank (プログレスタンク Puroguresu Tanku) is the handle sticking out of the Hazard Trigger. It is filled with an enhancement agent named Progress Vapor (プログレスヴェイパー Puroguresu Veipā), a reinforcement agent developed from Nebula Gas components, and has the ability to raise Hazard Levels. This agent reacts with Transgel Solid inside of Fullbottles and turns them into metallic components, During transformation, the Progress Vapor is poured through the Hazard Ride Builder (ハザードライドビルダー Hazādo Raido Birudā) and processed into reinforced equipment along with the contents of the Fullbottles, creating the Hazard Suit.
  • The BLD Ride Connector (BLDライドコネクター BLD Raido Konekutā) is the grey part sticking out of the bottom of the Hazard Trigger. It connects the trigger to the BLD Ride Port (BLDライドポート BLD Raido Pōto) top of the Build Driver. Responsible for developing the Hazard Ride Builder.
  • The Security Clear Cover (セキュリティクリアカバー Sekyuriti Kuria Kabā) conceals the BLD Hazard Switch, preventing accidental pressing during battle.
  • The blue button on the Hazard Trigger is known as the BLD Hazard Switch (BLDハザードスイッチ BLD Hazādo Suitchi'), which is used to activate the switch itself before use. Once transformed, pressing it allows access to Max Hazard Mode and the first turning on vortex crank will bring Build to Overflow (オーバーフロー Ōbāfurō) Mode, raising the both the Hazard Level again fighting ability, which is potent enough to inflict fear upon both enemy and ally alike. Upon entering Overflow Mode, turning the vortex crank on Build Driver for the second time will allow Build access to his Hazard Finish (ハザードフィニッシュ Hazādo Finisshu), a powerful Rider Kick.


"Like I thought, they went out of control. Wanna know how you can stop their power? The forbidden item created by Katsuragi... the Hazard Trigger."
―Blood Stalk revealing the Hazard Trigger to Sento[src]

The Hazard Trigger, dubbed the "forbidden item" by its creator Takumi Katsuragi, can massively boost the Hazard Level of its user, with deadly side effects. Attached to the Build Driver, it upgrades Kamen Rider Build's standard two-Fullbottle forms into Hazard Forms, granting him great strength. However, after several minutes in a Hazard Form, Build will lose consciousness and go on a rampage, attacking anything that moves. The Hazard Trigger can be used to permanently upgrade a Smash, but if that Smash is defeated afterwards, they will die.

According to Soichi Isurugi, a user might be able to overcome its side effects if their Hazard Level is high enough. The Unstoppable Hazard Sento eventually manages to overcome its side effects entirely by creating the FullFull RabbitTank Bottle, upgrading RabbitTank Hazard Form into RabbitRabbit Form and TankTank Form. The Treacherous Deathmatch

To access Hazard Forms, the BLD Hazard Switch is pressed before attaching the Hazard Trigger to the Build Driver above the Vortex Charge. The Build Driver is then used normally, triggering a transformation into a Hazard Form instead of a normal Best Match form. The Devil's Trigger While in a Hazard Form, the Build Driver's Vortex Lever can be cranked again to trigger the Hazard Attack (ハザードアタック Hazādo Atakku) finishing move. If the BLD Hazard Switch is pressed again to trigger Max Hazard mode, the Vortex Lever can be cranked again to activate Overflow (オーバーフロー Ōbāfurō) Mode, turbocharging Build's strength, and once more to activate the Hazard Finish (ハザードフィニッシュ Hazādo Finisshu) attack. The Unstoppable Hazard

With the Hazard Trigger in Max Hazard Mode, the FullFull RabbitTank Bottle can be inserted into the Build Driver to upgrade RabbitTank Hazard Form into either RabbitRabbit Form or TankTank Form. In these forms, the Hazard Finish is upgraded into the RabbitRabbit Finish (ラビットラビットフィニッシュ Rabitto Rabitto Finisshu) or the TankTank Finish (タンクタンクフィニッシュ Tanku Tanku Finisshu). The Counterattack Hero

To permanently upgrade a Smash into a Hazard Smash, the Hazard Trigger is hooked up to a special machine which the subject will lie in to be infused with the Hazard Trigger's power. The Forbidden Item

Hazard Forms

Kamen Rider

Two Bottles

FullFull RabbitTank Bottle



  • Being a non-collectible device that can be slotted into the main Rider's Driver to access an upgrade recalls the Genesis Driver's Core Unit that can be attached into the Sengoku Driver.
    • While it does not replace any portion of the Build Driver, it does possess the same process of modifying the "armor". However, the difference of each form is seen in the visor as the modified armor retains the same design for any form using the Hazard Trigger, with the suit's design appearing more symmetrical; similar to the Jimber Arms forms accessed by the Sengoku Driver.
      • The only other devices that impact the basic design of the suit are the Cross-Z Dragon adapter due to using one Fullbottle for the transformation, and the Cross-Z Magma Knuckle for the same reason, except its use completely alters the base suit.
      • It would later be enhanced with the FullFull RabbitTank Bottle, forming additional armor over the Hazard Suit.
  • The aspects of being a "Forbidden Device" and being used in response to the enemy's increasing power are shared with the Armed Saber from Kamen Rider Hibiki.
    • The comparison is further emphasized by how its combination with the FullFull RabbitTank Bottle provides additional armor as a similar indication that the form is now usable by the Rider.
  • Its impact on the Rider Form's appearance and the risk of causing volatile behavior are reminiscent of the Fang Memory from Kamen Rider W. Both devices are also used to access their titular rider's super forms.
    • A key difference is that, while FangJoker's control is dependent on the user's compatibility with the Joker Memory, according to a novel, Hazard Forms only require a high Hazard Level to neutralize the side effect. This has been exemplified by weapon-wielding Super Best Matches, as opposed to the unseen half changes with the Fang Memory posessing either the Metal Shaft or the Trigger Magnum.
  • The Hazard Trigger's negative effects on its user's mental state are similar to the Sclash Driver's, although the Hazard Trigger's effects are much more dangerous and uncontrollable.
    • Unlike other forms that cause Riders to go berserk, the Hazard Trigger's effects are not wild and aimless; the user loses all awareness of anything except the urge to destroy, and will fight with all their skills and no mercy.
  • Hazard Form's upgrade with the FullFull RabbitTank Bottle appears as an inverse of Kuuga's Forms, where as Rising Mighty becomes Amazing Mighty by enhancing a colored Upgrade Form into a singular, black Super Form, Hazard Form gains two distinctly colored Super Forms by adding new armor to the black Hazard Suit.
    • The additional armor is similar to the Gamers for Levels 3 and onward from Kamen Rider Ex-Aid where it depicts the theme of the form before merging with the Rider.
    • The design of the armor pieces seem to stem from the shoes of the respective Half Body, noticeably with the red arrows found on the "cuff" of the Rabbit Foot Shoes being applied to both ends of the Dimension Springers and the Tank Roller Shoes being more emphasized as the Blue Tank Rollers.


See Also