This article is about a/an set of alternate worlds in Kamen Rider Decade.

The characters of Kamen Rider Decade exist amongst various iterations of reality within the series referred to as an A.R. World (Another Rider's / Alternate Reality World). The Nine Worlds (9つの世界 Kokonotsu no Sekai) are the A.R. Worlds that are based on the previous entries of the Kamen Rider Series that have aired during the Heisei period of Japanese history. Each differs in some way from the series on which it was based. The New Worlds (新たな世界 Aratana Sekai) are the A.R. Worlds that are not based on a previous entry of the Kamen Rider Series from the Heisei period.

A.R. Worlds

Originally, Tsukasa only knew that their destinations were nine A.R. Worlds to finish their journey. As the story progressed, they realized that their journey doesn't end at the ninth world, but further more towards new worlds, until Decade connects these worlds' stories through him. The A.R. worlds are alternate realities in Decade's point of view.

Nine Worlds

New Worlds


Worlds with no relation to Decade


In the novel re-imagination of the Kamen Rider Decade TV series, Kamen Rider Decade: The World of Tsukasa Kadoya ~The Garden Inside the Lens~, the Nine Worlds are not alternate realities, but in fact the original worlds. The Hikari Studio group has already traveled to 6 different worlds when the novel begins, leaving only Den-O, Kuuga and Kabuto’s world unexplored.