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Icon-den-o.png 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 card

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

Imagin Possessions

Kamen Rider Mini Den-O

Plat Form

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

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.png Kamen Rider Den-O
Kamen Riders
Ryotaro Nogami - Yuto Sakurai - Past Man - Kotaro - Kotaro Nogami - Gaoh - Negataros - Ghost Imagin - Shiro - Kuchihiko - Mimihiko - Reiji Kurosaki - Eve - Anna
Transformation Devices
Den-O Belt - Rider Pass - K-Taros - Zeronos Belt - Zeronos Cards - New Den-O Belt - Gaoh Belt - Yuuki Belt - Golden Khakkhara - Pure Silver Metal Stick - G Den-O Belt
DenGasher - DenKamen Sword - ZeroGasher - Denebick Buster - DenGasher (New Den-O) - GaohGasher - Nega DenGasher - Momotarosword - Uratarod - Kintaros Ax - Ryuvolver - Ghost Imagin's sword - Shiro's Whip - Shiro's tops - SavageGasher - Golden Khakkhara - Pure Silver Metal Stick - DenGasher (G Den-O)
Rider Machines
Machine Den-Bird - Machine ZeroHorn - Machine GaohStriker - Machine Nega DenBird - Machine New Den-Bird
Time Transports
DenLiner - ZeroLiner - KingLiner - New DenLiner - GaohLiner - Nega DenLiner - Ghost Train - Battleship of Oni
The Ally Imagin and the Support Characters
The Taros: Momotaros - Urataros - Kintaros - Ryutaros

Other: Sieg - Deneb - Teddy - Futaros

DenLiner: Owner - Naomi - Hana - Stationmaster
Milk Dipper: Airi Nogami - Seigi Ozaki - Isse Miura
The Imagin
Contract holders
Kai - Death Imagin
Bat Imagin - Chameleon Imagin - Crust Imagin - Crow Imagin - Rhino Imagin - Ivy Imagin - Owl Imagin - Whale Imagin - Wolf Imagin - Jelly Imagin - Tortoise 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 - Pandarabbit Imagin - Snail Imagin - Oct Imagin - Armadillo Imagin - Albinoleo Imagin - Snowman Imagin - New Mole Imagin - Pink Rabbit Imagin - Clown Imagin - Ghost Imagin - Phantom Imagin - Shadow Imagin - Piggies Imagin - Mantis Imagin

Other: Gelnewt