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Kamen Rider Saber Episode 29 Preview
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Rintaro who decided to finally make his move, advances. He tells Mei that he will return to Touma, but before that, he goes to face Master Logos alone to determine the truth as a swordsman. Upon hearing this, Touma and his colleagues think that Rintaro is in danger and try to rush the Southern Base. Rintaro meets Master Logos and asks him of his true intentions. What is the true purpose of Master Logos? A new swordsman stands before Rintaro. His name is Ryouga Shindai, also known as Kamen Rider Durandal. He notices as the Seiken from that very same swordsman starts to point towards Rintaro.

This marks the full debut of Ryoga Shindai and his first transformation into Kamen Rider Durandal.

It turns out Master Logos was the one who did all of the events like Sophia's kidnapping, branded Touma as a traitor, turning the Northern Swordsmens against him, and purposely let him have the Primitive Dragon Wonder Ridebook, just so he would evolve even further for his twisted plans. And, now Master Logos have determined to have Touma annihilated and sends his enforcer; Ryoga Shindai to kill him.

Ren eventually defected from the organization to find Kento on his own and seeks to join him, despite Rintaro's warning about Kento's current condition and his power to seal the Seiken, only to be defeated and lost his ability to transform into Kenzan after the Fuusoken Hayate was sealed.

Rintaro is now determined to leave the Sword of Logos and joins with Touma in order to find the actual traitor within the organization, but not before confronting the Master Logos for the truth, only for Ryoga appears before him and prepares to eliminate him for defying the Master Logos and seeing this as an act of treason. Upon hearing this, Touma and the others rushed back to the Southern Base to quickly rescued him.

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The True Identity of 11th and Final Swordsman
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Now, we know about the identity of the mysterious man, which was none other than the older brother of Reika Shindai herself; Ryoga Shindai (神代 凌牙 Shindai Ryōga). Like his sister, he has blind loyalty towards the current Master Logos.

He transforms into the new Kamen Rider Durandal (仮面ライダーデュランダル Kamen Rāida Deyurandaru) by inserting the Ocean History Wonder Ridebook (オーシャンヒストリーワンダーライドブック Ōshan Hisutorī Wandā Raido Bukku) into the currently unnamed Seiken. However, despite being called a sacred sword, it can turn into a trident too.

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Valkyrie's New Form & New Zetsumerisekeys
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In the Zero-One Others: Vulcan & Valkyrie, Yua will get her new and final form: the Justice Serval (ジャスティスサーバル Jasutisu Sābaru). She accessed this form the Serval Tiger Zetsumerisekey (サーバルタイガーゼツメライスキー Sābaru Taigā Zetsumeraisukey), which was previously used by Sold20 in the Zero-One Others: Kamen Rider MetsubouJinrai.

Not only Yua who has gained the new Zetsumerisekey, but Isamu is also gained the Dire Wolf Zetsumerisekey (ダイアウルフゼツメライズキー Daia Urufo Zetsumeraizukī) and with his Assault Grip to the said Zetsumerisekey, he will transform into a currently unnamed form, which was previously used by Sold9 in the Zero-One Others: Kamen Rider MetsubouJinrai.

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Brief Synopsis of Zero-One Others: Vulcan & Valkyrie
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The story takes place after the first installment of the Zero-One Others. Kamen Rider MetsubouJinrai was originally created by the members of MetsubouJinrai.net (Horobi, Jin, Ikazuchi, and Naki) in order to stop Leon Arkland's scheme to mass-produce the soldier-type Humagears called "Sold" (ソルド Sorudo) and sells them worldwide.

Unfortunately, while they combined and transform into the said Kamen Rider, the Massbrain Zetsumerisekey (マスブレインゼツメライズキー Masuburein Zetsumeraizukī) leads the collective entity to destroy their original selves and now seeks to achieve peace by destroying both ZAIA Enterprise and MetsubouJinrai.net, becoming the main antagonist in the second installment. It's up to both Isamu and Yua to stop Kamen Rider MetsubouJinrai and save the members of MetsubouJinrai.net.