Kaiden Bugster is a Bugster who emerged from the data of samurai-themed game called Giri Giri Chambara and an antagonist in Kamen Rider Ex-Aid.
The Kaiden Bugster first emerged from Heiji Uesugi, a detective investigating Zero Day due to the death of his son during it. Kaiden spawned from him after he developed stress from being unable to solve the case. After being fought off by Kamen Rider Brave, Kaiden retreated back into Uesugi.
Kaiden later emerged again from Uesugi from his stress on the lack of progress he had made on the case. Fighting Brave again, Kaiden was defeated by the Kamen Rider with a Drago Knight Critical Strike. His debris was promptly collected by Kuroto Dan with the Gashacon Bugvisor.
Kaiden would go on to emerge again at Level 40 from a member of the band Neironzu. He ended up being destroyed again by Kamen Rider Snipe.
Kaiden was later used by Parado to complete Kamen Rider Chronicle, appearing as a boss within the game. He was destroyed by Ride-Player Nico. His powers were later channeled by the final boss of the game, Gamedeus.