Publication Information
- Host : Koichi Sakakibara
- Japanese : 榊原 耕一
- Riders : Kamen Rider Ryuki
- Gender : Male
- Season : Kamen Rider Ryuki
- Motif : Red Japanese Dragon, Medieval Knight
- Rider Type : Hero
- Homeworld : Earth
- First Appearance : Kamen Rider Ryuki Special : 13 Riders
- Last Appearance : Kamen Rider Ryuki Special : 13 Riders
- Number of Appearances : 1 (Ryuki Special)
- Portrayer : Keiichi Wada
Story
He is a man who lived in an apartment where Shinji found a Card Deck that led him to become Kamen Rider Ryuki. He disappeared prior to the start of the series, possibly eaten by Dragreder. In the 13 Riders TV special, Sakakibara is the original Ryuki. He saved Shinji but as he could no longer go on due to the severity of his injuries, he passed his deck on to Shinji as he dissolved inside the Mirror World. After Koichi faded, Shinji became Kamen Rider Ryuki and tried to prevent the other Riders from fighting as his way to thank Sakakibara.
Form
Unlike Shinji, he only shown to be assume normal standard form in 13 Riders TV Special.
- Kamen Rider Ryuki
- Height : 190 cm
- Weight : 90 kg
- Punching Power : 10t (AP: 200)
- Kicking Power : 20t (AP: 400)
- Maximum Jump Height : 35m
- Maximum Running Speed : 72km/h
- Sight and Hearing : 15km radius This is Ryuki's standard form that he had throughout most of the series, obtained once he forms his contract with Dragreder. A "balanced" Rider with equally powerful melee and far-range fighting capabilities, he uses the Drag Visor gauntlet on his left forearm to use Advent Cards.
- Attack Vent (AP : 5000) : Summons Dragreder.
- Sword Vent (AP : 2000): Conjures the Drag Saber : Dragreder's broadsword-like tail.
- Strike Vent (AP : 2000) : Attaches a dragon-like gauntlet on his right hand to shoot a burst of flames, assisted by Dragreder.
- Guard Vent (AP : 2000) : Attaches dragon-like shield arrays on his arms.
- Final Vent (AP : 6000) : Dragreder is summoned to assist with Ryuki's Dragon Rider Kick. It consists of him jumping into the air, delivering a flying side kick powered by Dragreder's flames.
- Koichi Sakakibara is portrayed by Keiichi Wada, who previously portrayed Ryo of the Heavenly Fire Star (RyuuRanger) from Gosei Sentai Dairanger, a Red Sentai Warrior that shares the same theme with Ryuki: both controlled Asian dragons who can breathe fire.
- Along with Yūta Mochizuki who had played Kouji Segawa (Kamen Rider J) and previously Yamato Tribe Prince Geki (TyrannoRanger), Koichi Sakakibara can be counted as the second time a main Kamen Rider was played by the actor who also portrayed a Red Ranger in Super Sentai series.
- He has the same name with the protagonist of the anime Another, Kouichi Sakakibara.
