Kamen Rider Decade Episodes

Ep# 	English title 	Japanese title 	Original airdate Kanji/Kana 	Romaji

1 	"Rider War" 	ライダー大戦 	"Raidā Taisen" 	January 25, 2009

After Natsumi Hikari has a nightmare of every Kamen Rider being defeated by a figure called Decade, she helps her grandfather Eijiro deal with unsatisfied customers. The photographer, Tsukasa Kadoya, seems to be at fault, but he simply tells Natsumi the photos are bad because he does not belong in this world. After the argument, various holes in reality open, allowing the Orphnochs, Undead, Makamou, Worms, Imagin, and Fangires to start terrorizing their world. In the bedlam, she finds a corroded belt and book, recalling it as Decade's from her dream. She gives Tsukasa the belt and book, allowing him to transform into Kamen Rider Decade by using a card from the book and inserting it into the belt. Using other cards, he fights the various monsters that have invaded his reality by transforming into Kamen Riders Kabuto, Faiz, and Hibiki. Back in his own reality, Tsukasa is warned by Wataru Kurenai that his reality is being superseded by the nine previous Kamen Riders' realities. He must go to their worlds and defeat the other Kamen Riders to save his own world, while Wataru keeps it frozen in place. Back in the Hikari Studio, Eijiro reveals a large photo that shows another world. Stepping outside, Tsukasa finds himself in this world as a police officer while Kamen Rider Kuuga appears to aid the police against two Grongi.

2 	"Kuuga's World" 	クウガの世界 	"Kūga no Sekai" 	February 1, 2009

Arriving in Kuuga's World, Tsukasa takes the guise of a policeman and watches Kuuga destroy a pair of Grongi, Ra-Dorudo-Gu and Me-Gyarido-Gi, before reverting to his human form, Yuusuke Onodera. Tsukasa later kills Go-Baberu-Da as Decade, but is mistaken for a Grongi by Yuusuke and Ai. When Yuusuke and Ai arrive at the Hikari Studio to discuss this strange Grongi, Tsukasa offers Ai his help in solving the mystery behind the Grongi's female targets and the location of their lair. On the foot of Mount Hitoki, the Grongi's Lair, Tsukasa reveals he used Ai as bait to lure out the remaining Grongi, revealing their plan to revive their leader before ruining their game. While attempting to destroy the Grongi, Decade is attacked by Kuuga, who reveals he knows about Decade's mission and will stop him at all costs. Natsumi pleads for them to stop, recalling her dream in which Decade and Kuuga seemingly destroy each other. A dimensional rift occurs, and their fight is interrupted by the appearance of Kamen Riders Kick Hopper and Punch Hopper.

3 	"Transcendence" 	超絶 	"Chōzetsu" 	February 8, 2009

After the fending off the Hoppers who disappeared into another dimensional rift, Yuusuke reveals he was told of Decade by a mysterious man. When Ai and her taskforce go to investigate Mount Hitoki, a black mist begins to rise from within, signaling the revival of N-Gamio-Zeda. Resurrected by the dimensional chaos, he uses his miasma to convert humans into Grongi. While Yuusuke saves Ai and takes her to the hospital, Tsukasa fights the Grongi alone. A dying Ai requests Yuusuke to overcome his angst and fight to protect everyone's smiles, and so Kuuga and Decade work together to destroy Gamio in a combo attack. After returning to the hospital, Yuusuke finds that Ai has died and vows to honor her dying wish. Meanwhile, Tsukasa and Natsumi return to the photo studio, preparing to leave for the next world in their journey.

4 	"Second Movement ♬ Kiva's Prince" 	第二楽章♬キバの王子 	"Dai Ni Gakushō ♬ Kiba no Ōji" 	February 15, 2009

Arriving in Kiva's World, Tsukasa and company discover that the Fangires of this world have made a truce with the humans. However, when Tsukasa finds the Lion Fangire attacking a young woman, he transforms into Decade to fight him. Wataru, the King of the Fangire Race, witnesses this and becomes Kamen Rider Kiva to fight him with the aid of his Arms Monsters, forcing Decade to assume Kamen Rider Kuuga's Mighty, Titan, and Dragon Forms to counter. Yuusuke manages to stop the fight, and the Swallowtail Fangire reveals that the young woman was actually a renegade Fangire. Yuusuke reveals he has promised to help Wataru, because he is uncomfortable with being the King. After meeting a mysterious man who is disgusted with the human/Fangire treaty, Tsukasa later encounters Kivahla, who uses her power to send him into another world where he is attacked by Kamen Rider Kaixa. Back in Kiva's World, after having fed on many humans, the Beetle Fangire arrives at Castle Doran with the intent to kill Wataru and take his place as the King.

5 	"The Biting King's Qualifications" 	かみつき王の資格 	"Kamitsuki Ō no Shikaku" 	February 22, 2009

While Tsukasa is fighting against Kaixa in another dimension, the Beetle Fangire defeats Wataru and becomes the new Fangire king, claming Kivat. After he declares Wataru's execution, Yuusuke covers the boy's escape as he takes refuge in the Photo Studio. After telling him of what had occurred, Tsukasa makes his way to Castle Doran to save Yuusuke as the Beetle Fangire absorbs the Arms Monsters. After shattering the Swallowtail Fangire, Decade encounters the Beetle Fangire, who fights him before assuming Kiva's DoGaBaKi form. When their fight makes way to Yuusuke and Wataru, the boy finds his courage to preserve harmony between the two races. He takes back the Kiva power and helps Decade battle the Beetle Fangire, mortally wounding him with a Darkness Moon Break/Dimension Kick combo. After learning that the Fangire, Wataru's father, was the man he met earlier, Tsukasa plays the violin for him before he shatters. As Yuusuke moves into the Photo Studio, Kivahla forces herself in, leading its occupants into another world.

6 	"Battle Judgement: Ryuki World" 	バトル裁判・龍騎ワールド 	"Batoru Saiban: Ryūki Wārudo" 	March 1, 2009

Upon arriving in Ryuki's World, Natsumi is arrested on suspicion that she killed the editor of the Atashi Journal: Reiko Momoi. To prove her innocence, Tsukasa acts as her lawyer in a Kamen Rider Trial, where the victor decides her fate.