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Icon-den-o.pngThis article is about a villain in Kamen Rider Den-O.

"I have the face for it, don't I?"
―Kai's catchphrase[src]

Kai (カイ) was the main antagonist of Kamen Rider Den-O. He was a Singularity Point from the future who was the mastermind behind the Imagin attacks, psychically giving them the orders to destroy the key to the Junction Point to ensure the future of the Imagin.


Arriving from the same alternate future as the Imagin race, Kai retained his physical body from being a Singularity Point. Using this to his advantage, Kai led the Imagins to change history and ensure their survival. To pick ideal dates to send Imagin back to, Kai uses a black page-a-day calendar where he has several hosts' memories and his own to pick from. To find these dates, he can look into human minds for strong memories much like the Imagin. When his own memories are used, a past incarnation of Kai appears in the past only to dissolve into a pile of sand. Kai is also capable of opening up portals through time and travel through it without the use of a time-traveling train, and through this ability can also release blasts of energy capable of erasing everything but himself from time and space. After mentioning how he feels about an event, he says "I have the face for it, don't I?" (俺、そういう顔してるだろ?, Ore, sōiu kao shiteru daro?). He often has an emotionless or angry expression on his face when he says this. Kai also has psychic abilities akin to Ryutaros', having the ability to control people as well as summon up a small troupe of break dancers.

He originally believes that the key to the Junction Point is the elder Yuto Sakurai, traveling back in time to January 10, 2007, to kill him. However, when the changes to the timeline from Sakurai's death are undone, he believes that Den-O is the culprit, and sends the Imagin Ryutaros to the DenLiner with a permanent ticket with the charge of killing Ryotaro. When Ryutaros refuses to follow through with his mission, Kai reveals himself and tries to get Ryutaros to sabotage the ZeroLiner, taking the DenLiner and Den-O Belt out of commission. After this fails, he notices that Yuto does not protect his future self from harm in the past, but rather protects Ryotaro.

After questioning him, Kai discovers that Airi is the one being protected, and Kai sends an army of Imagin to kill her. As Airi's memory loss and other quirks confound him, Kai creates the Death Imagin from all his remaining memories and will. Kai's army destroys the city until he finally discovers that the key to the Junction Point is not Sakurai or Airi but rather their child, the Singularity Point Hana. After Den-O, Zeronos, and their Imagin partners protect Hana by destroying the Death Imagin, all of Kai's memories are used up and he dissolves away into sand, taking all of the Imagin except for the Tarōs, Deneb, Sieg, and a few other isolated cases with him.



Kai was portrayed by Hideo Ishiguro, who later portrayed the titular protagonistIcon-crosswiki.png in Ultraman OrbIcon-crosswiki.png.


  • The true origins of Kai's background have remained a mystery, and what is known about him is that he is a Singularity Point from the Imagins' future. According to the first volume of THE Kamen Rider EX, it suggests Kai might be the child of Airi Nogami from his timeline.[1]


  1. THE Kamen Rider EX April 3, 2014 ISBN: 978-4091051448
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