Dex Stewart (A.R. World)

Kotaro Minami (南 光太郎) is the original Kotaro Minami's first incarnation from Kamen Rider Decade.

History
He is a man who fights the Crisis Empire as Kamen Rider Black RX (仮面ライダーBLACK RX), able to become either Robo Rider (ロボライダー), or Bio Rider (バイオライダー). However, with Dai-Shocker appearing in his world, he finds himself outmatched by the new monsters while searching for his friend Joe the Haze. Natsumi Hikari convinces him that Tsukasa Kadoya is not the Destroyer of Worlds that he heard about. Though he eventually learns of Joe's fate, Kotaro is not saddened as his friend would be with him in spirit.

When Tsukasa makes it back to Kotaro's world, he uses his Kamen Rider Black card to summon the other Kotaro (in person, and not as a manifestation). Kotaro and his counterpart battle side by side.

All Riders vs. Dai-Shocker
In Kamen Rider Decade: All Riders vs. Dai-Shocker, just as most other A.R. World riders, this Kotaro's existence is presumably ignored, and the original Kotaro Minami appears - although in his movie appearance, the original Kotaro was portrayed as identical to this version of the character.

Rider Card
Kamen Ride: Black RX: A Rider Card containing the power of Kamen Rider Black RX.

Kamen Rider Diend first used the card in the World of Decade, summoning Agito alongside Super-1 and Agito to fight Doctor Shinigami and the Dai-Shocker Soldiers in the 7-Eleven promotional campaign.