Hirohiko Sato

Kamen Rider Ryuga is a Dark Rider who murdered and assumed the guise of the Negatives World counterpart of Hirohiko Sato (佐藤 博彦, Satō Hirohiko), Natsumi's TG Club high school classmate. He is destroyed by Decade Complete Form with the Ryuki Survive Final KamenRide.

Earlier, in the World of Faiz, Narutaki summoned a version of Ryuga to finish off Decade, who at the time was unable to transform. This one was defeated by Diend using the Kiva Arrow.

Forms
Like the original Ryuga, Hirohiko transforms into Kamen Rider Ryuga through his Advent Deck and his V-Buckle.

Kamen Rider Ryuga
Being a copy of Ryuki, Ryuga is "balanced" Rider with equally powerful melee and far-range fighting capabilities, he uses his black Black Drag Visor gauntlet on his left forearm to use Advent Cards from summoning his Drag Saber. His Final Vent is Dragon Rider Kick, jumping into the air to emit dark energy that paralyzes the opponent's legs and then deliver a flying side kick with Dragblacker flying behind to boost the attack's power with its dark flame. Apparently, it's not as powerful as Ryuki's, as when the two collided, Ryuki's Final Vent won out and killed Ryuga.
 * Height: 1.90m
 * Weight: 60kg
 * Punching power: 250 AP (12.5t)
 * Kicking power: 450 AP (22.5t)
 * Vision and Hearing: 17 km approx
 * Maximum Jump Height: 40m
 * Maximum Running Speed: 80km/h

Contract Monster
Modeled after a Chinese dragon and Ryuga's Contract Monster, Dragblacker is referred as the Darkness.