|This article is about a/an rider in Kamen Rider Ryuki.|
Blank Form (ブランク体 Buranku-tai) is Ouja's default form when his Mirror Monsters are destroyed. It's much weaker than any other form and any of the other Riders, though it's enough to keep him from disintegrating in the Mirror World.
First shown in Kamen Rider Ryuki: Episode Final.
- Height: 200cm
- Weight: 98kg
- Sight & Hearing: 15km
- Maximum Running Speed: 100m/5s
- Maximum Jump Height: 40m
- Punching Power: 250AP
- Kicking Power: 400AP
This is Ouja's standard form that he had throughout most of the series, obtained once he forms his contract with Venosnaker. A melee-based Rider, Ouja's fighting style helped him in his victories more often than any of his Advent cards, using the Veno Visor (ベノバイザー Beno Baizā) scepter to conjure his spiral-bladed Veno Saber. His Final Vent is Veno Crash (ベノクラッシュ Beno Kurasshu), running at an opponent with Venosnaker slithering behind before raising its head up as is master jumps back towards it and the Miror Monster launches him so he can deliever a rapid bicycle kick at the target. Once defeating Gai and Raia, he had access to both their contract monsters and their Advent cards, becoming an even more dangerous force to be reckoned with the Unite Vent to create Genocider so the Final Vent Doomsday is used, with Ouja corkscrew kicking his opponent into a vortex that materialized on Genocider's torso.
- Height: 198cm
- Weight: 97kg
- Punching Power: 350AP
- Kicking Power: 550AP
- Maximum Jump Height: 60m
Kamen Rider Ouja Survive (仮面ライダー王蛇サバイブ Kamen Raidā Ōja Sabaibu) is Ouja's ultimate form, which only appeared in the first Ryuki's S.I.C. Hero Saga story in Monthly Hobby Japan magazine, Kamen Rider Ryuki: Advent Calendar (MASKED RIDER RYUKI -アドベントカレンダー- Kamen Raidā Ryūki: Adobento Karendā). This form is acquired when Ouja stole the Survive Shippu card from Kamen Rider Knight, becoming more powerful than his other forms. From the magazine, his contract monster Venosnaker, is also able to change into a more powerful version, Venoviper (ベノバイパー Benobaipā), and combine it with other stolen contract monsters to form Genosurviver (ジェノサバイバー Jenosabaibā).
Kamen Rider Ouja had the most Advent Cards out of any of the Riders. This was because he obtained two extra decks of cards by contracting with two of the Mirror world monsters that were previously contracted with Riders he defeated.