Kotaro Kirigakure
- Voiced by: Ai Orikasa
The defacto-leader of the Ganba Team, taking on the identity of "Yellow Ganba." He pilots the Go Tiger and is the main pilot of Ganbaruger, and pilots it alone once Rikiya and Yosuke get new robots.
- Bratty Half-Pint: To say he is an obnoxious little bugger would be an understatement.
- Super-Speed: His Yellow Ganba suit gives him the ability to move with blinding quickness.
- Sitcom Arch-Nemesis: He tends to be this with Chinatsu.
Rikiya Ryuzaki
- Voiced by: Bin Shimada
An aspiring baseball player taking on the mantle of "Red Ganba." He pilots the King Elephant and later Revolger.
- Big Brother Instinct: He is very protective of his little brother Tetsuya, who ends up being the main force to get him out of his Dai-Makai-induced brainwashing.
- The Big Guy: He is the guy with super strength, after all.
- Ship Tease: With Katsura.
Yosuke Kazamatsuri
- Voiced by: Omi Minami
A somewhat nerdy young boy taking on the role of "Blue Ganba." He pilots the Mach Eagle and later Gekiryuger.
- Everyone Can See It: His crush on Yurika is known to everybody but her.
- My Beloved Smother: His mother pushes a lot of studying on him, and that's not even going to into forcing him to take violin lessons.
- The Power of Love: If it weren't for Yurika, he would not have been of any help when against the mochizuki Makaijuu.
- The Smart Guy: He's usually the first one to figure out how any of the mechanics work. He also has to study a lot thanks to his mother.
Toubei Kirigakure
- Voiced by: Kenichi Ogata
Kotaro's father who teaches ninjutsu. He gets turned into a dog in the first episode, forcing him pretend to be his own family's new pet, "Gonzales."
- Catchphrase: "This is bad."note
Chinatsu Yuuki
- Voiced by: Yuri Shiratori
Kotaro's Childhood Friend who's always looking for a scoop.
- Loves My Alter Ego: Kind of; she fights with Kotaro, but shamelessly fangirls over Yellow Ganba (and the Ganba Team in general).
- Sitcom Arch-Nemesis: With Kotaro, with whom she argues with a lot.
Katsura Takeda
- Voiced by: Rika Fukami
The daughter of the defense force's general and member of the class committee alongside Rikiya.
- Daddy's Girl: She is very close to her "papa", which probably influenced her mostly negative opinion of the Ganba Team.
- Depending on the Writer: Her relationship with Chinatsu (and by extension Yurika) can vary between the episodes; sometimes, they're all friends, other times, Katsura is all stuck up and mocking towards Chinatsu, to the latter's anger.
- Loves My Alter Ego: She's the only one of the three designated love interests that doesn't have this; she likely has a higher opinion of Rikiya than she does for any member of the Ganba Team.
- Ship Tease: With Rikiya. Her status as a love interest is probably the least obvious of the 3 (contrasting Yurika, who is the most obvious), but nonetheless, she and Rikiya are shown to be quite close during the ending.
Yurika Komaki
- Voiced by: Ikue Otani
Chinatsu's friend and the object of Yosuke's affection.
- Loves My Alter Ego: She fell for Blue Ganba after he rescued her, unaware that he and Yosuke are the same. This being Yosuke, hearing this causes him to hastily decided it doesn't matter if he becomes a dog, much to Kotaro and Rikiya's dismay.
- Oblivious to Love: She just thinks of Yosuke as a friend, without the slightest hint of noticing that he might feel differently.
- Official Couple: Hinted at in the ending, after she finds out that Yosuke and Blue Ganba are one and the same.
General Takeda
- Voiced by: Tomomichi Nishimura
The head of the defense force and Katsura's father. He previous appeared in Zettai Muteki Raijin-Oh.
- Doting Parent: Towards Katsura.
- Recurring Character: As noted above, he's the only character other than Eldoran to appear in all entries of the franchise. We actually see him more here than in Raijin-Oh, likely because this town is where he lives.
Eldoran
- Voiced by: Bin Shimada
The same guardian of Earth who created the Earth Defense Class. He charges the battle with the Dai-Makai to the Ganba Team whilst he holds by Gokuark from returning.
- Recurring Character: Due to being the character the franchise is named after.
Yaminorius III
- Voiced by: Kazuyuki Sogabe, Eiji Sekiguchi (Sunrise Eiyuutan series)
A servant of Gokuark who works to wreak havoc on the human world until his master can be freed.
- Amnesiac Dissonance: He accidentally loses his memories while disguised as the human "Mr. Yamino", where he proves to be a friendly guy and even strikes a bit of a romance with Aiko, the boys' homeroom teacher. Even after this is resolved, however, she does not forget about it and spends the rest of the series trying to convince him to be better.
- The Dragon: He is Gokuark's top servant.
- How the Mighty Have Fallen: His life clearly falls apart over the course of the series, going from proud demon general to Butt-Monkey, to the point he's practically a hobo sleeping on benches in the late game despite still being the main threat of the show. He even ends up summoning a cooking-themed Monster of the Week just because he hasn't had a good meal in months.
- Nice Job Fixing It, Villain: Gokuark probably would've ended up winning at the halfway point in the series if Yaminorius wasn't so overeager to help, that he ended up distracting his master long enough for the Ganba Team to finish him. This causes a second incident down the line: after his resurrection, Gokuark drops Yaminorius like an old sock because of his aforementioned mess-up, prompting a proper Heel–Face Turn from his ex-general.
Gokuark
- Voiced by: Masaharu Sato
A king of the Dai-Makai who was released for short time before being resealed by Eldoran, but he sends out his servant in hopes of being free once again.
- Back from the Dead: He is defeated halfway through the series through a combination of the Revoluger's Last Fire and Gekiryuger's Dragon Thunder Flash, but is brought back near the end.
- Big Bad Duumvirate: With his brothers. He seems to be primary Big Bad of the series, though, as he is more active.
Seiyark
- Voiced by: Ken Yamaguchi
Another king of the Dai-Makai sealed away.
- Big Bad Duumvirate: With his brothers.
- Shock and Awe: He controls lighting.
Retsuark
- Voiced by: Bin Shimada
The third king of the Dai-Makai sealed away.
- Big Bad Duumvirate: With his brothers.
