Rumi Ichijo
She is a girl who is the daughter of the doctor killed by Badan. She gives Ryo temporary peacefulness.
Dr. Hajime Kaido
He is Ryo's father's friend and is the researcher of the biochemistry which is also the teacher of a university. He cooperates in Ryo unstintingly.
Shizuka Murasame
She is the newspaper reporter who is Ryo's elder sister. While investigating rumor of UFO with Ryo, she was caught by Badan. Since she got to know Badan's secret, she was executed with the electric chair.
Shiro Kazami / Kamen Rider V3
He is the oldest Rider to appear out of suit. He is the leader of the Japanese division of the Rider Organization while Kamen Riders 1 and 2 are in America. Apparently the strongest of the Senior Riders as he was the only one able to hold off ZX.
Joji Yuki / Riderman
The second oldest Kamen Rider in the special. He is V3's partner in leading the Kamen Riders when Kamen Riders 1 and 2 are away.
Kazuya Oki / Kamen Rider Super-1
The youngest of the Sempai Riders, he tried to persuade ZX into joining the riders without having to fight.
Series:  Kamen Rider ZX