Morio Makino
Head of the mecha department for SGS. He works in his own "Makino Workshop" where Boukenger arsenal is held and is next to the gougou vehicle hanger. The Boukenger refer to him as Sensei. In episode 35, Morio disguised himself as Akashi and Askahi as Mario to trick the Dark Shadow. In the last episode, Morio used his disguising abilities to trick everyone into thinking he was Sakura when she followed Akashi into space.

Mister Voice
Missions are dispatched by their mysterious boss with a male voice. He appears to them in three wall screens with a character image that emotes how 'he' feels or rather how 'he' wants to seem. Turns red when angry. The screens beside him show images of great artifacts. In episode 47-49, a mysterious girl had followed Masumi as he defected and then was in hiding the Brain of Gordom from Gajya. She and the Precious was protected by the Boukenger. She was later revealed to be the one behind Mr. Voice, using a voice-altering device and software.
Morio did seem to know who she was but the Boukenger not so much. According to the second Chouzenshuu book, she was Leon Giordana, whose sketchbook was used to make the Neo-Paralel engines and Gordom Engines. Leona, who she is referred to as now, found 'Soul's Reincarnaiton' 500 years ago and this is the soul's 11th reincarnation. She is currently around 13 years old.

DaiKenjin Zuban
This precious of the Lemurian (also spelled Remurian) Civilization came thats first seen form is that of the Golden Sword (Sage Sword Mode) and when the seal of the Saken Mode is broken, Zuban can transform into a human-sized fighter (Saken Mode). He also can become the size of DaiBouken. First appeared in Episode 29. The Boukenger were first hestitan to have him around, considering him a dangerous precious but later learned how needed he was and accepted him as a member of the team. The SGS wants them to protect him. His powers are at full force with happiness, he powers down and becomes hostile when there is aruging, fighting and sadness. He doesn't speak Japanese but does understand it, he mostly repeats his name and similar words. He is most attached to Akashi being he was the one that pulled him out of the stone. He was last seen as the Golden Sword wielded by BoukenYellow.

People Worth Mentioning

Kazuko Karamonoya
The Boukenger and Shizuka go to her house/import store in search of two important dolls. When infilitrated by the Dark Shadow, Kazuko notices Natsuki's bracelet and Natsuki inquires if she knows anything about it. Kazuko confies to Natsuki that the dolls are special to her, one that she entrusts in Natsuki and another that eventually lands in the hands of Gajya. The dolls have a map to leads to an Island that held the real Precious. Gajya used Lazuko as a pawn to get the other doll. She later reveals to Natsuki, in a way, that she is the last of the Lemuria Civilization which Zuban is from. She was seen in Episodes 9, 10, 11, and 33.

She appears in Episode 13 and she is considered a burglar, trying to find a Precious that the Jaryuu are after as well. She has powers as well, she puts together he Dragon Neck Ball, the Buddhist Stone Bowl, Hourai Ball Branches, a Firerat Fur Coat, and a Swallow's Cowrie Shell to bring a bit of a forest that has the Raiment and Potion. Shouta is smitten with her. It is later alluded to that she is Princess Kaguya.

Nendogami of the Dark Shadow disguised himself as a younger sister of Natsuki in episode 14 and implanted fake memories making Natsuki not trust Masumi. She never had a little sister as far as we know.

Magi's apprentice who was mostly seen as his Jaakuryuu form in Episodes 15-16. Once a human, he sacrificed his humanity in order to survive without water and was transformed into a Jaakurby Ryuuwon, who dispatched him to find the Aqua Crystal. He could not regain his composure until Satoru took him under his protection. Played by Gaoranger' s Takeru Shibaki.

An elder from the City of Water who did not want to see any more of his people perish in the search for the Aqua Crystal. Turned Ragi's section of the Crystal Document into water, but Satoru remembered it from earlier and helped Ragi find the Crystal. Ragi and Magi were reunited as the ocean returned.
[Episodes 15-16]

Shirou Masaki
Appears in a flashback in Episode 4 and Gai takes his appearance in Episode 18. One of Satoru's ex-partners who went on an expedition with him years ago. While searching for a Precious, Satoru accidentally set off a trap ended up killing Masaki and their other partner Kyoko before Satoru could even leave to find help. Later on, Rei tricked Satoru into believing that Gai was Masaki, still alive, so he could shoot him with the Fighter's Crossbow. Eventually the illusion was broken.

Eiji's Ashu mother. When Satoru, Shouta, and Natsuki go to Eiji's home, they are addressed to by a woman in white with white hair in a mirror. She appears in Episode 19, she lets go a crystalized form of a tear, which Natsuki takes and eventually gives to Eiji in Episode 20. Eiji's demon form resembles his mother's form. She is remembered by her son in Episode 40 because her soul can't 'pass on' unless Eiji dies. In Episode 41, while his soul is in Purgatory he meets up his mother much to his surprise. She takes him to a facsimile of their home. In Episode 42, it is found out that she was actually Ouga in disguise and her real spirit gives him his old staff to permanently vanish the demon. She transports him back to the corporal world. In episode 48, Eiji returns home and is comforted by her, in a seemingly physical form, she tells him that he accomplished the family mission and reminds him that he thrists for adventure. She then disappeared.

Kouichi Akashi
Satoru's father, a Cryptozoology Hunter made an appearance in 'Boukenger the Movie: The Greatest Precious'. He responded to Muse's call to obtain a prehistoric insect Stingross said not to exist. He and Satoru had been distanced because of their thoughts about what is an adventurer. After confronting Hyde Gene, Kouichi aknowledges Satoru as an adventurer and a son to be proud of. It also seemed as if he and Morio met before. He got possession of a watch Satoru lost.

Toba Yuji
Toba was Souta's partner during his spy life who appears in Episode 23. He kidnapped Souta for the Ashu Clan to find the loaction where SGS keeps the precious. He betrayed them and saved Souta when he set a bomb in the Quester Robo. Souta told him that he moved on and he should to as well, he said he'll try but continued as a spy.

Natsuki/Lelina's Parents
Protrayed by Eri Tanaka (MegaYellow of Megaranger) and Keisuke Tsuchiya (KirinRanger of Dairanger) during flashbacks and a projected message during Episodes 33 and 34, they placed their daughter in a sleeping capsule that slowed down her aging to give her a peaceful future due to their empire's downfall. Their dying wish was for her to be happy.

In Task 38, Souta had helped a stray cat with her leg and she was eternally greatful. While Shizuka was stealing a transforming Preicous called the Rainbow Cloth, a piece broke out and transformed Miyuu into a girl. She thought that as a woman, she could make Souta happy. She paid him back for helping her by defeating Shizuka and retrieving the Precious. He adopted her afterwards. She was never seen again.