This article is about a/an duplicate character/rider in Kamen Rider Den-O.
Not to be confused with Kotaro Nogami, Ryotaro's grandson, who became New Den-O

"Kotaro" is the eleven-year old version of Ryotaro Nogami (野上 良太郎 Nogami Ryōtarō) that he met during the events of Kamen Rider Den-O: I'm Born!, nicknamed Kotaro to differentiate him from his present, older self.

I'm Born


Both Ryotaros.

When Ryotaro and Hana are trapped in the year 2000 by Kamen Rider Gaoh they encounter Ryotaro's child self. With Ryotaro lacking memories of being Kamen Rider Den-O due to being attacked by Gaoh and unable to transform, the young Ryotaro is given the nickname Kotaro and decides to go with them to stop Gaoh's plans. During a fight with ninjas in the Edo Period, Momotaros possesses him with his contract to Ryotaro extending to the past and transforms into Kamen Rider Mini Den-O.

After the battle Kotaro is brought back to his time but not before seeing his late parents and then bids the gang farewell.

Video Game appearances

Kamen Rider Battle: Ganbaride

Kamen Rider Chibi Den-O appears as a playable character in this video game.


Kamen Rider Chibi Den-O card


Plat Form
Kamen Rider Mini Den-O (platform)

Plat Form

Plat Form (プラットフォーム Puratto Fōmu) is Mini Den-O's most basic default form undersuit, which is briefly seen during Mini Den-O`s transformation sequence before the Aura Armor and the Denkamen facemask attaches.

Sword Form
KR-Mini Den-O

Sword Form Mini

"Sword Form!"
―Transformation announcement[src]

Rider Statistics

  • Rider Height: 115 cm.[1]
  • Rider Weight: 45 kg.[1]

Ability Parameters:

  • Punching Power: 2.5 t.[1]
  • Kicking Power: 3.5 t.[1]
  • Maximum Jump Height: 17.5 m.[1]
  • Maximum Running Speed: 100 m. per 7.5 sec.[1]

Kamen Rider Den-O Sword Form Mini, alternatively Kamen Rider Mini Den-O (仮面ライダーミニ電王 Kamen Raidā Mini Den'ō), is the form accessed by Mini Den-O when possessed by Momotaros.

This form is exclusive to Kamen Rider Den-O: I'm Born!


  • Den-O Belt - transformation device belt that allows for form switching.
  • Rider Pass - a ticket system that allows for transformations as well as the operation of the motorbike Machine DenBird and DenLiner
  • DenGasher - a four-piece standard issue assemble side-arm that reconfigures to form various weapons.


  • DenLiner - a time-traveling bullet train
  • DenBird - Den-O's bike. Also operates the DenLiner.


  • In I'm Born, unlike later Child Riders Wataru and Asumu, Kotaro does not grow to the size of an adult when transforming into his Rider Form, becoming Kamen Rider Mini-Den O.
    • When Mizoguchi later portrayed the de-aged Ryotaro, he instead grew to an adult size when transforming into his Rider form, although by this time of production, Mizoguchi had grown into a young teenager.


  1. 1.0 1.1 1.2 1.3 1.4 1.5 Kodansha. (2007). Kamen Rider Den-O: Double Action x4+2. p. 54. ISBN 978-4061791626.

See also

Icon-den-o Kamen Rider Den-O
Singularity Points
Ryotaro Nogami - Yuto Sakurai - Kotaro Nogami
Transformation Gear
Den-O Belt - Rider Pass - Climax Cellphone K-Taros - Zeronos Belt - Zeronos Card - New Den-O Belt - Gaoh Belt - Yuuki Belt - G Den-O Belt
Combination Armament DenGasher - DenKamen Sword - ZeroGasher - Denebick Buster - Combination Armament New DenGasher - GaohGasher - Combination Armament Nega DenGasher - Savage Gasher - Combination Armament G DenGasher
Rider Machines
Machine Den-Bird - Machine ZeroHorn - Machine New Den-Bird - Machine GaohStriker
Time Trains
DenLiner - Zero-Liner - New DenLiner - GaohLiner - Nega DenLiner - Ghost Train - KingLiner
The Ally Imagin and the DenLiner Crew
The Taros: Momotaros - Urataros - Kintaros - Ryutaros

Other: Sieg - Deneb - Teddy

DenLiner: Owner - Naomi - Hana - Station Master
The Imagin
Contract holders
Death Imagin - Kai
Bat Imagin - Chameleon Imagin - Crust Imagin - Crow Imagin - Rhino Imagin - Ivy Imagin - Owl Imagin - Whale Imagin - Wolf Imagin - Jelly Imagin - Tortoice Imagin - Scorpion Imagin - Spider Imagin - Bloodsucker Imagin - Molech Imagin - Cobra Imagin - Salamander Imagin - Gecko Imagin - Newt Imagin - Wasp Imagin - Bluebird Imagin - Rabbit Imagin - Anthopper Imagin - Kraken Imagin - Mole Imagin - Leo Imagin - Panda Rabbit Imagin - Snail Imagin - Oct Imagin - Armadillo Imagin - Albinoleo Imagin - Snowman Imagin - Pink Rabbit Imagin - Clown Imagin - Ghost Imagin - Phantom Imagin - Shadow Imagin - Piggies Imagin - Mantis Imagin
Evil Riders
Gaoh - Nega Den-O - Kamen Rider Yuuki (Skull Form) - Kamen Rider Yuuki (Hijack Form) - Kuchihiko - Mimihiko - G Den-O
Community content is available under CC-BY-SA unless otherwise noted.