Kamen Rider Wiki
Kamen Rider Wiki
Icon-amazons.png This article is about a/an rider in Kamen Rider Amazons.

"I'll checkmate you in (number) move(s)."
―Amazon Sigma's pre-battle taunt[src]

Jun Maehara (前原 淳 Maehara Jun) was the scout of the Nozama Peston Service. After his death at the hands of the Dragonfly Amazon, he was revived by transplanting Amazon Cells into his corpse. He used the Amazons Driver to become Kamen Rider Amazon Sigma (仮面ライダーアマゾンシグマ Kamen Raidā Amazon Shiguma).


  • Identification code: Unknown
  • Rank: Unknown
  • Destroyed by: Mole Amazon


Original Life and First Death


"I don't mind being eaten, as long as it's you."
―Jun's last words.[src]

Jun was originally a member of the Nozama Peston Services and an Amazon hunter. He met his untimely end during the hunters' confrontation with the Dragonfly Amazon, formerly Ryusuke Otaki, attempting to get through to his former comrade only to be mauled by the hungry Amazon. Mortally wounded, Jun takes solace in that, though fated to die at the hands of one of the beasts, it was Otaki who did the deed as he dies. BEAST INSIDE


Sometime after his first death, Nozama Pharmacy, lead by Yugo Tachibana, received his corpse, and implanted Amazon Cells into his body. While this action revived him, it resulted in him turning into his Amazon Origin form. Jun was also seen chained up in a cage, waiting for the moment to go outside. HERO OR NOT

Amazon Sigma, now face to face to Alpha

Amazon Sigma during his fight against Alpha

Takaaki Tenjo ordered Shogo Kano to give Jun his own Amazons Driver, which allowed him to transform into Amazon Sigma, an Amazon Rider similar to Alpha and Omega. His first deployment was used as a trap to kill Jin Takayama; Yugo sent an e-mail to him, which mentioned "a new type of Amazon". During his first battle, he was able to easily overpower Amazon Alpha, severely wounding him and forcing him to retreat.INTO THE CANNIBAL'S POT

In his first encounter with his old friends, the Nozama Peston Services, he then fights and overpowers Haruka Mizusawa, even managing to deliver a near-fatal blow through Omega's torso. JUNGLE LAW

Afterwards, he received a maintenance check in Nozama Pharmacy. His next deployment was to intercept Jin, who was chasing the Tlaloc switch stolen by Shogo Kano. While he managed to defeat Alpha easily once again, Jin refused to admit defeat; when questioned by this, Jin stated that he simply didn't want to, which was something that the dead would never understand.

Immediately after the fight, Nozama Peston Services and Haruka came, with Jin recovering and joining the fray not long after. In the ensuing battle, Amazon Sigma was able to stay toe-to-toe against the duo of Alpha and Omega. However, he was later caught off-guard by an electric bullet combination from Kazuya Misaki and Kota Fukuda, who were his previous teammates. Taking the chance to strike, Amazon Alpha finished him with the Violent Slash, followed by Omega's Violent Strike.

Second Death

Amazon Sigma, impaled by his old friend and killer, Mamoru.

Even after all of the punishment he received, Amazon Sigma was still able to stand, as if nothing happened to him. However, Jin revealed to everyone that Jun, being a Sigma-Type Amazon, didn't feel any pain whatsoever due to being already dead; his body started to dissolve, with the damage to it finally taking its toll. When he realized this, it was too late for him; when he started attempting to escape, his torso was impaled from behind by Mole Amazon, finally killing him for good. KILLING DAY

The news of his death reached Takaaki Tenjo quickly; he became enraged by this, thinking that he was being used as an "accessory to failed research" by Yugo Tachibana. He then stated that despite Amazon Sigma's massive amount of power, a lifeform who doesn't eat is "nothing but garbage".

It is likely that the project was ultimately discontinued and no other Sigma-Type Amazons were produced anymore, except for one that surfaced five years later.

Video Game appearances

Kamen Rider Buttobasoul

Kamen Rider Amazon Sigma medal

Kamen Rider Amazon Sigma is a playable character in Kamen Rider Buttobasoul.

Powers and Abilities

Little was known about Jun's abilities while he was a living human, other than him being a skilled hacker and fighter. He was also an accomplished chess player, the latter of which is often referenced in his fights as an undead Amazon; he used this to taunt his opponents, correctly measuring how many moves he would take to finish them off.

As a biological weapon designed and built to surpass the 'old' Amazon in every way, his basic fighting abilities as an undead Amazon is easily on par with that of Alpha's and Omega's. However, his lack of morality and sense of pain boosts his parameters significantly, enabling him to easily take on Alpha or Omega on one-on-one fights, and almost defeating them altogether after being upgraded. However, his lack of sense of pain also serves as his greatest weakness; he is unable to gauge the damage he has taken during fights, which causes him to overexert himself often, thereby taxing his regenerative abilities heavily.

As an undead with no need, as well as being incapable, of consuming food, he is forced to rely on researchers back in Nozama Pharmacy for maintenance of his wellbeing. His overall abilities are also dependent on how good said researchers are at their jobs in maintaining and upgrading him, since he is thoroughly incapable of growth in any way. This makes him a deadly weapon, though he is one that is easy to control.


Sigma Driver-less.jpg
Amazon Origin (アマゾン素体 Amazon Mototai)[1] is Amazon Sigma's initial form before equipping the Amazons Driver. In his case, it appears to be identical to his default form.

This form is exclusive to S1 Episode 8

Amazon Sigma

Amazon Sigma

―Transformation announcement[src]

Rider Statistics:

  • Height: 186.5 cm[2]
  • Weight: 91.9 kg[2]

Ability Parameters:

  • Punching Power: 23.3 t[2]
  • Kicking Power: 29.1 t[2]

By using a specialized Amazons Driver made by Tachibana and his crew, it allows Jun to transform into Amazon Sigma.

Thanks to the newly developed Amazon Cells that are implanted in his body, he doesn't need to eat to restore his energy to transform again. Also, the belt gives him the ability to not feel pain; this acts both as an advantage and an disadvantage, as shown during his debut and his final death.


  • Sigma Header (シグマヘッダー Shiguma Heddā): The antenna. It is able to detect noise and enemy presence in his surroundings.
  • Amazon Eye (アマゾン・アイ Amazon Ai): The eyes. It is able to change focus at will and catch a target 1k meter away, even if they are at high speed.
  • Crusher (クラッシャー Kurasshā): Sigma's fangs. They are sharp and can easily chew through steel.
  • Converter Lung (コンバーターラング Konbātā Rangu): Sigma's chest. With the Amazons Driver's influence, the Amazon cells harden themselves to protect the core inside by cancelling almost all damage. It can also absorb heat and wind from the surrounding and convert it to stock energy.
  • Shell Break Arm (シェルブレークアーム Sheru Burēku Āmu):The arm cutter that can give the enemy severe damage to the internal hub.
  • Shell Break Leg (シェルブレークレッグ Sheru Burēku Reggu):The boot cutter that can momentarily activate the cell and enhanced motor function.
  • Knee Hex (ニーヘクス Nī Hecusu): The knee protectors that can observe the quake and strengthen the knee.
  • Wilder Crust (ワイルダークラスト Wairudā Kurasuto):The skin. It can moderately fasten and stretch the joints and muscles, also can change the hardness of parts of the body to defend from an enemy's attack.


  • Violent Strike

Appearances: S1 Episodes 9-11



Behind the Scenes


Jun Maehara is portrayed by Hiroshi Asahina (朝日奈 寛 Asahina Hiroshi). As Amazon Sigma, his suit actor is Makoto Arakawa (荒川 真 Arakawa Makoto).

Concept Art


  • Kamen Rider Amazon Sigma's appearance is a recolor of Haruka Mizusawa's Amazon Origin form, but with his own Amazons Driver equipped.
    • Sigma's color scheme is highly reminiscent of a red-bellied piranha.
  • Being a Sigma-Type Amazon, Jun shares similarities to the Necro-Overs from Kamen Rider W.
  • He and Jin are presumably the only Amazons who don't need to use an Amazons Register to control themselves.
  • In the western release of Kamen Rider Amazons, Amazon Sigma is known as Amazon Rider Sigma.
  • Ironically, the cause of his two deaths was by his teammates from Nozama Peston Service; as a human, he was killed by his comrade-turned-Amazon Ryusuke Otaki, and as an Amazon, he was killed by Mamoru.
  • Sigma is the only Amazon Rider (along with the movie-exclusive Neo Alpha) not to have a Ridewatch representing his Rider form.
  • Jun Maehara shares his first name whith Jun Shibaura/Kamen Rider Gai from Kamen Rider Ryuki, Jun KiyamaIcon-crosswiki.png/DenziYellow from Denshi Sentai DenzimanIcon-crosswiki.png and Jun YabukiIcon-crosswiki.png/Yellow4 from Choudenshi BiomanIcon-crosswiki.png.

Dark Amazon


See Also


Icon-amazons.png Kamen Rider Amazons
Kamen Riders
Haruka Mizusawa - Jin Takayama - Jun Maehara - Chihiro - Einosuke Mido
(Neo) Amazons Driver - (Neo, Militant) Amazons Register - Junglaider
Other characters
Mizuki Mizusawa - Nanaha Izumi
Nozama Peston Service
Makoto Shido - Ryusuke Otaki - Nozomi Takai - Kazuya Misaki - Kota Fukuda - Jun Maehara - Mamoru
Nozama Pharmacy
Reika Mizusawa - Shogo Kano - Yugo Tachibana - Takaaki Tenjo
Team X
Hiroki Nagase - Kenta Kitamura - Takumi Yamashita - Chihiro
Yugo Tachibana - Shogo Kano - Takeshi Kurosaki - Ichiro Fudamori - Kota Fukuda - Iyu Hoshino - Mizuki Mizusawa
Experiment Amazonz
Spider Amazon 1 - Spider Amazon 2 - Bat Amazon 1 - Dragonfly Amazon - Mole Amazon - Queen Ant Amazon - Soldier Ant Amazon - Butterfly Amazon 1 - Butterfly Amazon 2 - Shrike Amazon 1 - Shrike Amazon 2 - Crab Amazon - Bat Amazon 2 - Wasp Amazon 1
Sigma type Amazonz
Amazon Sigma - Crow Amazon
New type Amazonz
Vulture Amazon - Panther Amazon 1 - Stag Beetle Amazon - Rhinoceros Amazon 1 - Snake Amazon 1 - Mantis Amazon 1 - Urchin Amazon - Baboon Amazon - Elephant Amazon - Weevil Amazon - Rose Amazon - Mantis Amazon 2 - Rhinoceros Amazon 2 - Panther Amazon 2 - Snake Amazon 2
Lysogenic type Amazonz
Amazon Neo - Jellyfish Amazon
Livestock Amazonz
Buffalo Amazon - Sea Snake Amazon - Shark Amazon - Snapping Turtle Amazon - Squirrel Amazon - Tiger Amazon