Kamata

Kamen Rider Abyss (仮面ライダーアビス) is a fictional character in the 2009 Kamen Rider Series Kamen Rider Decade. Unlike other Kamen Riders to appear in the other iterations of reality in Decade, Abyss is original to the series and did not originally appear in Kamen Rider Ryuki although his contract monsters, Abysshammer and Abyssslasher, did.

Fictional character biography
Kamata (鎌田) is actually the Paradoxa Undead (パラドキサアンデッド), a Category King Undead who was brought into Ryuki's World by Narutaki. Assuming the guise of sub-chief editor of the Atashi Journal appeared to support Tsukasa and company in their investigation the scene of chief editor Reiko Momoi's murder to clear Natsumi Hikari, helping provide whatever info he could before he and Tsukasa are summoned to join the Kamen Rider Trial in the Mirror World.

When Imperer interferes in the fight, Abyss decides to take advantage of this turn of events to see Decade's abilities, overseeing the later fight between Decade and Knight before attempting taking them and Ryuki out. But once Ren acquires the Time Vent from Odin, Shinji uses it so he and Tsukasa can stop Reiko's murder, learning that Kamata is the culprit, using his Undead powers to kill Reiko. After being defeated by Decade and Ryuki, with his deck shattered, Kamata's true nature as an Undead is revealed by Narutaki who takes him back to his home: Blade's World.

Kamata returns to the World of Blade where he works with Hajime in a plot to take over the world as the chairman of the BOARD Corporation. After helping Hajime steal the three other Rider Systems, Kamata helps him create the Joker Rouse Card. He is later defeated alongside the Joker by Decade and Blade.

OOO, Den-O, All Riders: Let's Go Kamen Riders
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Kamen Rider Wizard
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Portrayal
Kamata is portrayed by Masato Irie (入江 雅人). As Kamen Rider Abyss, his suit actor was Eitoku (永徳), who later becomes the suit actor for Kamen Rider Diend.