Male. Kamen Rider Ex-Aid. A Rider of action games and an intern working in the pediatrics department of Seito University Hospital. Sixteen years ago, he was in critical condition following a traffic accident but was saved by a certain doctor. After receiving a game console from that doctor, he found joy in his bleak life and decided to become a doctor himself to save others' lives.

Male. Kamen Rider Brave. A Rider of role-playing games. A surgeon working at Seito University Hospital. The son of Hospital Director Kagami Haima, he is a genius surgeon who returned to Japan to become a Kamen Rider. He transforms into a Kamen Rider to fight the Bugsters. Although he looks down on Emu, he is a tsundere type who joins forces because they share the same goal of exterminating Bugsters. He refers to the four main Ex-Aid Riders by titles: Emu is "Intern," Taiga is "Unlicensed Doctor," and Kiriya is the relatively normal "Coroner."

Male. Kamen Rider Sniper. A Rider of gun-shooting games. He was once a doctor, but his license has been revoked as of the start of the story. In the past, while fighting Bugsters as a Kamen Rider for the secret department CR (Cyber Rescue Center), he failed to cure the Game Illness of Hiiro's girlfriend, Saki, leading to her death and his subsequent ban from transforming into a Kamen Rider.

Male. Kamen Rider Lazer. A Rider of racing games. Despite his flashy, playboy-like appearance, he is a medical examiner. He keeps a close watch on Hojo Emu and the other Riders.

Male. Kamen Rider Genm. The CEO of Genm Corp, the game company that developed all the systems governing Kamen Riders. In cooperation with the Ministry of Health, he established the CR and developed the Gamer Drivers and Rider Gashats, providing them to suitable candidates to support the war against the Bugsters. While his speaking style is very sly and oily, he shouts "Henshin!" with total seriousness when transforming into Genm.

Female. A staff member dispatched from the Ministry of Health to the CR (Cyber Rescue Center), a top-secret department established within Seito University Hospital to fight Bugsters in secret. Within the hospital, she acts as a nurse under the name Karino Asuna. However, her true identity is Poppy Pipopapo. As Poppy, she switches from her nurse outfit to colorful clothing and her personality becomes bubbly and lighthearted. Since most of the main characters know her true identity, she is usually called "Poppy Pipopapo" rather than "Karino Asuna." She is also Kamen Rider Poppy.