|“||I am Hiryu Kakogawa. Sougo Tokiwa, we are fated to cross paths countless times.||„|
|~ Hiryu introducing himself.|
|“||Live for the present? What nonsense! You understand nothing about the tragedy of not being chosen! So, I'm going to give this a try. I'll steal everything from you and say the same thing back to you!||„|
|~ Hiryu to Sougo after becoming Another Zi-O II.|
Hiryu Kakogawa is Another Zi-O and a major antagonist in Kamen Rider Zi-O.
On April 24, 2009, Hiryu and Sougo were the only two survivors of a bus crash that killed everyone including their families. Though the bus crash was caused by the Time Jacker Sworz, Hiryu grew to believe that Sougo was the cause of the crash due to Tsukuyomi (who had traveled back from the future) calling out Sougo's name just before the crash.
Hiryu later obtains the Zi-O Anotherwatch from Sworz, allowing him to transform into Another Zi-O. Blaming Sougo for his parents' deaths, Hiryu sought to use his Another Rider powers to exact revenge. He began going after former Another Rider hosts to harvest their Anotherwatches for him to use, in the process coming into conflict with Zi-O, Geiz and Woz.
While going after Hayase, Hiryu fought against all three Riders in the Another Rider forms he had acquired and beat back Kamen Rider Woz Futuring Quiz. Hiryu then revealed his Another Zi-O form and fought Zi-O II in a fierce battle. Hiryu later leaves to run after Hayase and steal the rest of Another Wizard's powers. Confronting Sougo, Hiryu tells him that the bus crash they were in took the lives of his parents and blames "the girl in the white dress" for it. Sougo and Hiryu then both transform and fight each other, only for their fight to be interrupted by Geiz. Geiz transforms into Geiz Revive and easily defeats Another Zi-O, but Sworz appears and retrieves him before he can be finished off.
Hiryu later assaulted Geiz, declaring that he would be the one to kill Sougo Tokiwa, but was overwhelmed by the power of Geiz Revive. To obtain more power, Hiryu began forcibly implanting Anotherwatches in people to turn them into Another Riders. With his Another Rider army assembled, Hiryu went to confront Sougo Tokiwa, only for his Another Riders to be defeated by Zi-O and Geiz before he himself was defeated by Zi-O. Knocked out of his transformation, Hiryu was comforted by Sougo, who encouraged him to stop dwelling on the past and to look towards the future.
Due to alterations to the timeline, Hiryu Kakogawa rose to become Oma Zi-O in 2019 instead of Sougo Tokiwa, becoming Another Zi-O II and commanding an army of Another Riders to enforce his rule. He was confronted by Sougo when he returned to 2019 and summoned Another AgitΩ, Another Den-O and Another Gaim to fight him. Though Sougo defeated his Another Riders, Hiryu simply altered history so that they survived.