|This article is about a/an transformation device in Kamen Rider Zero-One.|
The Zaia Thousandriver consists of the following parts:
- Rise Slot (ライズスロット Raizu Surotto) - The right-hand slot used to insert Progrisekeys into the Driver. Learning is performed when a Progrisekey is inserted and the Key's Rider Model (ライダモデル Raida Moderu) is sent to the Fusion Reactor. Pushing a key within the slot will activate Thouser's Thousand Destruction finishing attack. If an alternate Progrisekey aside from Amazing Caucasus is exchanged and inserted without removing the Awaking Arsino Zetsumerisekey, the user can perform the Break Rise finisher.
- Zetsumerise Slot (ゼツメライズスロット Zetsumeraizu Surotto) - The left-hand slot used to insert Zetsumerisekeys into the Driver. Learning is performed when a Zetsumerisekey is inserted and the Key's Lost Model (ロストモデル rosuto Moderu) is sent to the Fusion Reactor.
- Thousand Equipper (サウザンドエクイッパー Sauzando Ekuippā) - The central golden circular section. it is an irradiation device unit that produces Thouser's Infrast Tecter bodysuit and other equipment during Perfect Rise (パーフェクトライズ Pāfekuto Raizu) via irradiation molding beams before being put on the wearer.
- Gate Liberators (ゲートリベレーター Gēto Riberētā) - The two doors that open up during transformation. When closed, they cover the Thousand Equipper as a security mechanism. When a Progrisekey and a Zetsumerisekey has been inserted, it will open, activating the Fusion Reactor. Once opened, it acts as a reflector, improving the accuracy of the irradiation molding beams.
- Fusion Reactor (フュージョンリアクター Fu~yūjon Riakutā) - The Driver's reactor located within the main body. By performing a fusion reaction with the Progrisekey's Rider Model and the Zetsumerisekey's Lost Model, Perfect Rise is initiated to convert the synergies between them into a form that maximises each Model's abilities, forming Kamen Rider Thouser.
The Zaia Thousandriver uses the Amazing Caucasus Progrisekey in conjunction with the Awaking Arsino Zetsumerisekey to transform the user into Kamen Rider Thouser.
To transform, the user inserts the Awaking Arsino Zetsumerisekey into the left-hand slot of the driver. Then, the user activates the Amazing Caucasus Progrisekey, opens it, and inserts it into the right-hand slot, causing the face of the driver to open and reveal a projection of Thouser's face. The Amazing Caucasus Rider Model and the Awaking Arsino Lost Model are then manifested from the Driver, before their horns interlock (with the Caucasus Beetle's Amazing Trident horns emitting pink light and the Arsinotherium's Awaking Lancer horns emitting sky blue light) and their bodies fuse with the user after the Infrast Tector inner suit materializes. Finally, the five horns are attached to the faceplate, generating the Thousand Eye Visor and finishing the transformation. To cancel the transformation, the user simply needs to eject both Amazing Caucasus Progrisekey and Awaking Arsino Zetsumerisekey altogether.
- Main article: Finisher (Zero-One)
Pushing the Amazing Caucasus Progrisekey again after transformation initiates the Thousand Destruction (サウザンドデストラクション Sauzando Desutorakushon) finisher.
- The Zaia Thousandriver is the second transformation belt in Kamen Rider Zero-One, and by extension the Reiwa era, to use the term "Driver".
- It is the first Driver in the Reiwa era to require two devices to transform.
- Requiring the face of the Driver to open in order to complete the transformation makes it similar to the Beast Driver, though the methods of doing so are different due to their respective collectibles for their series.