Kamen Rider Decade

"I'm just a passing-through Kamen Rider! Remember that!" ― Tsukasa

Though the protagonist of Kamen Rider Decade, Decade is treated as a villain due to Narutaki prophecy of the Rider War that he causes.

History
Originally, Tsukasa was the leader of Dai-Shocker who lost his memories and ended up in another world where he was found by Natsumi Hikari and works for her grandfather as a photographer. However, when Natsumi is sucked into pocket dimension where finds the Decadriver, Tsukasa learns from a youth named Wataru Kurenai that this world will end, and that he is needed to protect it. After finding Natsumi, Tsukasa becomes Kamen Rider Decade to battle the various monster while confused by both his actions and the cards' powers' fading. When time suddenly freezes, Wataru appears, revealing the status of the worlds and assigning Tsukasa the task of traveling into the other worlds to stop the dimensional chaos inflicted on his own world by meeting the nine Riders of each of the other dimensions. Along joined by the World of Kuuga's Yuusuke Onodera, Kamen Rider Kuuga, Tsukasa traveled to Worlds of Kuuga, Kiva, Ryuki. While visiting the Worlds of Blade and Faiz, Tsukasa encounters Daiki Kaito, Kamen Rider DiEnd as he ventured to the World of Agito.

Upon arriving in the World of Den-O, Tsukasa becomes involve in the adventures of Kamen Rider Den-O as he helps them fight the Oni Rider Brothers before returning to the present time to continue his journey to the Worlds of Kabuto and Hibiki. With the journey appearing to be over, Tsukasa returns to what appears to be Natsumi's world, only to learn it is an alternate universe called the World of the Dark Riders. There, refusing to live in such a world, Tsukasa gains the K-Touch that enables him to become Complete Form to take out most the Dark Riders. Knowing that their journey is not really over, Tsukasa and the Hikari Studio group venture to the Worlds of DiEnd and Shinkenger, confronting the Ayakashi Chinomanako who threatens the latter world's balance when he obtained DiEnd's powers.

While visiting the Worlds of Black RX, Black, and Amazon, Tsukasa confronts Apollo Geist of Dai-Shocker. Soon after, Tsukada arrives to the World of Decade, his home world. There, tricked by Nobuhiko Tsukikage to beat the other Kamen Riders in a tournament, Tsukasa regains his memories as the leader of Dai-Shocker and resumes his place in the organization. However, Tsukasa finds himself overthrown by Shadow Moon and a revenge-driven Sayo as Priestess Bishium through Rising Ultimate Kuuga. After meeting Joji Yuki a former Dai-Shocker scientist, Tsukasa resolves to stop Dai-Shocker and leads all the Kamen Riders to defeat them while makig peace with Sayo.

However, arriving the World of the Rider War, Tsukasa learns that the worlds he saved are still merging and ceasing to be because of his actions while facing the Fangirezed Super Apollo Geist. Once Apollo Giest is destroyed, Tsukasa learns we was supposed to destroy the Kamen Riders of the alternate worlds with the nine original version Kamen Riders gathering to force Decade on the path he is suppose to take. Accepting his fate, Decade destroying many Riders and turning them into cards. He is assisted by Yuriko Misaki, Electro-Wave Human Tackle. However, when finding himself facing Natsumi as Kamen Rider Kivala, Decade allowed himself to be destroyed as his actions and death are the catalyst to restore the worlds at the cost of his existence. However, Natsumi finds a way to revive him through the use of a picture and the A.R. Riders' memories. From there, Decade leads the A.R. Kamen Riders against Super Shocker before he and Kamen Rider Double team up to destory Ultimate-D. With his mission over, Tsukasa resolves to travel the worlds.