Paradoxa Undead

Paradoxa Undead appeared in 2009 TV series called Kamen Rider Decade. His real name is Kamata (鎌田) who was Kamen Rider Abyss (仮面ライダーアビス Kamen Raidā Abisu) which 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 Abysslasher did.

Kamata is actually the Paradoxa Undead (パラドキサアンデッド Paradokisa Andeddo), 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 to take 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.

In the World of the Rider War, a copy of the Paradoxa Undead was created by Super Apollo Geist by combining Undead. This Paradoxa Undead is destroyed by Kiva.

The Paradoxa Undead and Capricorn Undead's fight Decade (as seen in Welcome to the Blade Restaurant) was shown in a recollection by Amadum as he explained the nature of his world as a paradise for monsters destroyed by the Kamen Riders. The Paradoxa Undead also appears in the world within the Magic Stone proper. The Kamen Rider Rings It was among the monsters whom were destroyed by a combination of Blade's Lightning Slash, OOO's OOO Bash and Agito's Rider Kick.

Powers and Abilities
He is able to create a blade-like wind from his forearm to kill his target.