As above stated, Kamen Rider Arc was a powerful leader of the Legendorga who led his race to glory, attacking any race that stood in his way, including monsters. However the original Kiva stood against Arc and defeated him. However, Arc was not gone for good, and his essence was sealed within a coffin. Years later, the place where he was sealed became the ground for a juvenile detention center, that includes Takashi Sugimura. When Sugimura tried to escape, he came across Arc's coffin. Arc then took over Sugimura's body before Sugimura used this new power to escape. When he did, he was picked up by the surviving members of the Legendorga Clan and brought to the castle. Arc's resurfacing commenced with the ressurection of his race. Arc and his raced commenced the takeover of humans and any race that stood in its way, while also targetting the current Kamen Rider Kiva, Wataru Kurenai. Eventually, he becomes enarmoured by Moka-sama's beauty and power that he decided to make her his queen, much to Gorgon's dismay. Arc attempted to make Wataru his servant through the Legendorga baptism, becoming Kiva's Dark Flight Style. Moka however, managed to get through to him by confessing her love to him and Wataru fought against Arc in a fierce battle, destroying Arc as Kiva Emperor Form and Flight Style with assistance from Castle Doran.
Kamen Rider ArcEditWith the assistance of Arc-Kivat , he can transform into Arc, the King of the Castle in the Demon World. As Arc, he wields the 4m long Arc Trident. He can shoot a light bullet from his forehead.
Legend ArcEditThrough the use of the Wake Up Fuestle (which resembles Rey's Key Fuestle), Arc transforms into Legend Arc by assimilating the demon-eye of the moon to obtain the full power of his race, growing wings and a second set of arms. In this form, Arc able to fly. In the process, Arc-Kivat assumes Mecha-Kivat mode as his persona cast comes off and yells, "Go to Hell."
As Legend Arc, he can open up the giant mouth/eye in his chest known as the Dead Crusher and create the Ultima Black Hole to perform the Ultima Dead End finisher with the destructive power of 120t.