Professor Osanai
He served as a counselor to the B-Fighters at Cosmo Academia.
Insect Elder Guru
He appears in Episode one and Forty-Seven. Guru is the one who gave the original B-Fighter their powers. Though he's aged, he is still able to help the B-Fighter in their times of need as he has extensive knowledge of the Melzard. Guru died trying to protect the insects of the world from the Dark Wave Motion power of Dargriffon. He was buried in the cave where Takuya first found him.
Yui Toba
Kouhei's younger sister, who goes to the same high school with him and his self-proclaimed manager. She covered for him when he has to leave school to fight off Melzard. She is in love with Kengo. She was frozen by Elebammoth, the first monster sent by the Melzard.
Kabuto
Kabuto is Guru's son who gave the original B-Fighters their Beet Ingram years ago and returned once more to visit his father's grave in Episode 50.
Juukou B-Fighter
The original B-Fighter go to assist them in the search for eight powerful medals but are infected by a virus that makes them fight each other. When the virus is frozen, they able to overcome it. They appear in Episode 25-28 and 47.