This article is about a/an alternate reality/A.R. World (another rider's world) in Kamen Rider Decade.

The World of Decade (ディケイドの世界 Dikeido no Sekai) is the version of reality that is the true home of Tsukasa Kadoya (Kamen Rider Decade). It is the primary setting of Kamen Rider Decade: All Riders vs. Dai-Shocker. The backdrop used to enter this world depicts an old mansion that is the home of the Kadoya family. This A.R. World is neither one of the Nine Worlds nor the New Worlds. This is the world where Daiki got his first treasure, the Diendriver.


Dai-Shocker members in the World of Decade

Kaijin from the Shōwa Kamen Rider Series
Gurongi from Kamen Rider Kuuga
Lords from Kamen Rider Agito
Mirror Monsters from Kamen Rider Ryuki
Orphnoch from Kamen Rider 555
Undead from Kamen Rider Blade
Makamou from Kamen Rider Hibiki
Worms from Kamen Rider Kabuto
Imagin from Kamen Rider Den-O
Fangire from Kamen Rider Kiva