Hitomi Sakuma
Takuya's girlfriend, a 20-years-old freelance photographer. She is the only person besides Spider-Man to ride the Spider Machine GP-7.

Shinko Yamashiro
Takuya's 18-years-old younger sister, who takes care of the household chores for the Yamashiro residence.

Takuji Yamashiro
Takuya's 7-years-old younger brother.

Dr. Yamashiro
Takuya's father. An astronomer who is killed during the first episode after his research led to the discovery of the Iron Cross Army.

An alien from Planet Spider. 400 years prior to the event of the first episode, he pursued the Iron Cross Army in search of vengeance after his homeworld was destroyed by them, but crash landed into the Earth and was imprisoned in an underground cave for centuries. He is the one injects the Spider Extract to Takuya.

Juzo Mamiya
An investigator in charge of Interpol's Secret Intelligence Division. He manages to uncover the fact that Spider-Man is Takuya and asks for his assistance in their mutual battle against the Iron Cross Army. From that moment onward, Takuya receives a radio transmitter from him, which allows Spider-Man to rendezvous with Interpol and vice-versa.