Kagen is a Quartzer who has the power to transform into Kamen Rider Zonjis and one of the two secondary antagonists of the movie Kamen Rider Zi-O: Over Quartzer.
Kagen and Jogen were sent into the Sengoku Era where they confronted Sougo and his friends, who had also traveled their. Transforming into their Rider forms, Sougo and co. fight off Kamen Rider Zonjis and Zamonas.
The two Quartzer Riders later return with their Time Mazines during the battle between Nobunaga's army and an enemy army. Despite bringing out their Time Mazines, the two are fought off again by Sougo, Geiz and Woz.
Kagen and Jogen later return in the present during the final battle and fought the Heisei Riders summoned by Sougo. Kagen was ultimately defeated by the first Reiwa Rider, Kamen Rider Zero-One.