The Nega-World's Dark Riders

is the twentieth episode of Kamen Rider Decade. It is the first part of the World of Negatives arc, the first of the New Worlds the Hikari Studio travels to following the journey across the Nine Worlds. This also marks the TV debut of Kamen Riders Ryuga and Orga after their respective movies.
==Synopsis==
to be added
==Plot==
With their tour of the nine Kamen Rider Worlds complete, the Hikari Studio group returns to their home world, finding it as it was before the monsters appeared. Tsukasa is the only one who feels something is not right and questions the reason for the journey. Before Yusuke or Natsumi can attempt to answer, they encounter the violinist Otoya Kurenai, who thanks them for saving the world and tells Tsukasa that he earned a world of his own for his journey. As Natsumi goes out to see her TG Club friends and teacher for a high school reunion, Tsukasa and Yusuke have a short encounter with Narutaki who congratulates him on getting his own world. Later, Tsukasa becomes the ten-thousandth customer in a restaurant and wins both a free meal as well as a vast fortune. Tsukasa enjoys the upper class lifestyle until he takes his leave during an arranged marriage meeting. Yusuke is forced to take his place, but he runs off upon realizing that the women are actually monsters in disguise. Elsewhere, while hanging out with her TG Club friends, Natsumi tries to figure out where her friend Chinatsu is, and the TG Club members take the opportunity to run off, with the teacher attacking a couple as Alternative. Tsukasa runs into Otoya who mentions a treasure before transforming into Dark Kiva and challenging him, along with the other members of the TG Club who become Ryuga, Dark Kabuto, and Orga. With Diend arriving to back him up for this treasure, Decade battles Dark Kiva. When Decade attempts to use his Final Attack Ride against Dark Kiva, the attack suddently cancels as he falls and reverts back to human. As the dark Riders leave, Tsukasa realizes that all of his Rider cards have turned black. Elsewhere, Natsumi is still searching for Chinatsu when she passes by someone in dirty and ragged clothing who turns out to be another Natsumi
==Cast==
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===Guest stars===
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*Restaurant Owner: 
*Maid: 
===Suit actors===
*Kamen Rider Decade: 
*Kamen Rider Diend, Kamen Rider Dark Kiva : 
* Kamen Rider Ryuga: 
==Rider Cards==
*Card Used:
**Decade:
***Kamen Ride: Decade, Ryuki
***Attack Ride: N/A
***Form Ride: N/A
***Final Form Ride: N/A
***Final Attack Ride: Decade
**Forms:
***Decade, Decade Ryuki
**Diend
***Kamen Ride: Diend
***Attack Ride: N/A
***Final Form Ride: N/A
***Final Attack Ride: N/A
DCD Ryuki EP20.png|DecadeKamen Ride: Ryuki
==Errors==
*Hirohiko/Ryuga's transformation sound reuses the casual sound rather than Ryuga's own.
*Kazuyoshi/Dark Kabuto and Kenji/Orga's Transformation devices lack any of their respective voice lines.
==Appearing monsters==
World of Negatives
*Mirror Monsters: Raydragoons
==Notes==
*As part of Super Hero Time, this episode aired alongside episode 17, .
*Viewership: 7.9%
==DVD releases==
Kamen Rider Decade Volume 5 features episodes 18-21: Idle Hibiki, Ending Journey, The Nega-World's Dark Riders and The Walking All-Rider Album. http://www.toei-video.co.jp/DVD/sp21/decade.html
Blu-ray Box comes with all 31 episodes.
==References==
==External links==
*TV Asahi's official summary for ｢ネガ世界の闇ライダー｣
*Toei TV's official episode guide for ｢ネガ世界の闇ライダー｣
Category:Kamen Rider Decade
Category:Episodes
Category:Crossovers
Category:New Kamen Rider Episode