Daiki is a mysterious young man who is portrayed as being cheerful to the extent of being annoying to those around him, but becomes serious in battle and sees material objects as more important than anything else. Narutaki, aware that Daiki is Diend, avoids getting in his way. He also appears to know about Tsukasa's past, referring to sea cucumbers as being something Tsukasa had always wanted to taste. He travels from A.R. World to A.R. World, stealing what he refers to as "treasures".
It is revealed that he comes from an A.R. World (referred to as the "World of Diend") where he was an officer who served the evil Fourteen who has deemed Kamen Riders as threats to the public peace. Daiki hunted them down and turned them in for education until he captured the leader of the Kamen Riders: Kamen Rider Glaive. When Glaive is unmasked, he is revealed to be Daiki's older brother Junichi.
By then, Daiki learns the truth that Fourteen brainwashes people, powerless to stop him. Losing his self-confidence and seeking to undo all of the mistakes he had caused, Daiki stole the Diendriver from Dai-Shocker, becoming Kamen Rider Diend and becomes Fourteen's new most wanted Kamen Rider.
He leaves his world, traveling to other worlds and taking their treasures as a means of self-delusion until he crosses paths with Kamen Rider Decade. Eventually, he does lackadaisically accept the Hikari Studio residents as "friends", even calling Decade a "comrade", though he is not beyond abandoning them without explanation, usually for his own self-interest. He also seems to be willing to steal from the weak and innocent, as he stole from Kurosaki when he was a child. This makes him one of the more questionable Secondary Riders when it comes to morality.
He mostly appeared as Kamen Rider Diend. Only in Episode 12 of Kamen Rider Decade, he briefly wore G3-X suit.
Kamen Rider Diend's ending theme is entitled "Treasure Sniper".
|“||Kamen Ride: Diend!||„|
|~ Transformation announcement|
- Height: 194cm
- Weight: 88kg
- Punching power: 6t
- Kicking power: 8t
- Maximum jump height: 30m
- Maximum running speed: 100m/5s
Diend only has access to a single form by using the Diend Kamen Ride Card in the Diendriver and then shooting the Diendriver above him. In this form, Diend can move extremely fast when he personally fights rather then use his Kamen Ride cards through the use of the microwave-emitting Tesla Bands around his wrists. Decade also has Tesla Bands, but does not use them. Diend can also perform the Blue Strike (ブルーストライク Burū Sutoraiku) attack.
Appearances: Episodes 10-15, The Onigashima Warship, 16-24, 26-27, All Riders vs. Dai-Shocker, 28-31, Movie War 2010, Episode Yellow, Let's Go Kamen Riders, Super Hero Taisen
|“||Final Kamen Ride: Diend!||„|
|~ Transformation announcement|
- Height: 201cm
- Weight: 107kg
- Punching power: 14t
- Kicking power: 16t
- Maximum jump height: 60m
- Maximum running speed: 100m/3.5s
This form appears in Kamen Rider × Kamen Rider × Kamen Rider The Movie: Cho Den-O Trilogy; similar to Decade's Complete Form (コンプリートフォーム Konpurīto Fōmu) with the exception of movie based main antagonistic Riders being on his chest armor instead of the main or secondary riders. While Decade's is powered by the protagonist Heisei Kamen Riders and their ultimate forms, Diend Complete Form is powered by the main antagonistic Kamen Riders of the Heisei Kamen Rider films (no Kamen Rider from a Den-O film is included):
- Kamen Rider G4
- Kamen Rider Ryuga
- Kamen Rider Orga
- Kamen Rider Glaive
- Kamen Rider Kabuki
- Kamen Rider Caucasus
- Kamen Rider Arc
- Kamen Rider Skull
- Height: 192cm
- Weight: 176kg
- Puching Power: 2.5t
- Kicking Power: 7.5t
- Highest Jump: 20m
- Top Speed: 100m/8s
- Vision and Hearing: 15km approx.
- Defense Rating: 10/10
In episode 12 of Decade, Daiki briefly deployed as G3-X to take out the Grongi with Yusuke Onodera supporting him. During the fight, Kaito takes off the armor to finish the Grongi off as Diend, revealing that he only became G3-X for his own agenda.
- Diendriver - Kaito's primary weapon and transformation device.
- Diend Belt (ディエンドベルト Diendo Beruto): A belt worn around Diend's waist which resembles the Decadriver, with its card scanner replaced with an empty casing which protrayed Diend's insignia. Said casing can be removed to insert his K-Touch.
- Card Holder (カードホルダー Kādo Horudā): A card holder which Diend use to contain his Rider Cards, in a similar manner to Decade's Ride Booker. It is stored on the left side of his Diend Belt and its maximum capacity is 18 cards.
- K-Touch - Diend's device that allows him to transform into Complete Form.
- Rider Cards - Gives access to Diend to power-up his attacks and summon any Kamen Riders, depending on which card used.
- Final Form Ride's - Unique weapons transformed from past Kamen Riders through the Final Form Ride cards
- Kiva Arrow - Transformed from Kiva via Final Form Ride: Kiva Arrow
- Blade Blade - Transformed from Blade via Final Form Ride: Blade Blade
- Jumbo Decadriver - Transformed from Decade via Final Form Ride: Decaderiver
- Ongekibou Rekka - Temporary weapon loaned to Diend in the World of Hibiki when against Bakegani
- Big Machine - Giant robot that combined from Gigant Horse and Crisis Fortress. Only in Super Hero Taisen.
- In Kamen Rider Decade: All Riders Super Spin-off, Kaito said he had a Rider Machine called Machine Diender (マシンディエンダー Mashin Diendā), even though Tsukasa pointed out to Kaito that he only stole his Machine Decader in Toei's cyan recolor room.
Kamen Rider X
Kamen Rider Amazon
Kamen Rider Super-1
Kamen Rider ZX
Kamen Rider Black/RX
Kamen Rider Kuuga