This article is about a/an villain in Kamen Rider Build and Kamen Rider Ex-Aid.

―Transformation phrase as Kaiser Reverse.[src]

―Transformation phrase as Bikaiser.[src]

Kaisei Mogami (最上魁星 Mogami Kaisei) resides in the World of Ex-Aid. Using the Nebulasteam Gun, Kaisei become Kaiser Reverse (カイザーリバース Kaizā Ribāsu), also referred as Right Kaiser (ライトカイザー Raito Kaizā). He is the World of Ex-Aid counterpart of Kaisei Mogami (World of Build).

Character History

As Kaiser Reverse, this Kaisei Mogami made his appearance before the Gamer Riders at Seito University Hospital. Taking claim for the Nebula Bugsters unleashed there. Following his counterpart in the World of Build, Mogami activated the World of Ex-Aid's Enigma device, causing the Gamer Riders' transformations to be cancelled and rendering them defenseless. Kaiser Reverse attempted to kill the doctors only to be met by Kamen Rider Ghost, who assumed Newton Damashii to defeat the Nebula Bugsters accompanying him. Seeing his advantage lost, Kaiser Reverse took his leave. Kamen Rider Heisei Generations FINAL: Build & Ex-Aid with Legend Riders


Sento was reminded of the unification of the two Kaisei Mogamis into Bikaiser when he witnessed Fu Washio transform into Hell Bros. The Counterattack Hero


This counterpart of Kaisei Mogami is louder and more ruthless, and is more focused on the annihilation of the Kamen Riders than the humans.


Nebula Hell Bro's
Gearless Bi-Kaiser

Nebula Hell Bro's

Nebula Hell Bro's (ネビュラヘルブロス Nebyura Heru Burosu) is the basic body of the Kaiser with no Gears attached. Though typically bypassed altogether in the transformation to Kaiser, it is briefly seen during the transformation to the combined Bikaiser. Kamen Rider Heisei Generations FINAL: Build & Ex-Aid with Legend Riders

Kaiser Reverse
Kaiser Reverse

Kaiser Reverse

"Gear Engine! Funky! (Rock music, engine revving) Engine Running Gear!"
―Transformation announcement[src]


  • Height: 202.0 cm.[1]
  • Weight: 103.5 kg.[1]

Ability Perimeters:

  • Punching Power: 20.3 t.[1]
  • Kicking Power: 24.8 t.[1]
  • Maximum Jump Height: 32.4 m.[1]
  • Maximum Running Speed: 100 m. per 2.8 sec.[1]

Kaiser Reverse (カイザーリバース Kaizā Ribāsu) is the red Kaiser, also named Right Kaiser (ライトカイザー Raito Kaizā), accessed by inserting the red Gear Engine into the Nebulasteam Gun.

Kaiser Reverse's finisher is the Funky Drive (ファンキードライブ Fankī Doraibu): Kaiser Reverse channels the power of a Gear and performs a powerful blast attack.

  • Gear Engine: Kaiser Reverse fires a large energy shot at the enemy, then follows it up with a roundhouse kick that leaves behind a trail of red energy.

Appearances: Heisei Generations FINAL: Build & Ex-Aid with Legend Riders



"Gear Engine! Gear Remocon! Funky Match! Fever! (Rhythmic beeping, engine revving) Perfect!"
―Transformation announcement[src]


  • Height: 202.0 cm.[1]
  • Weight: 108.0 kg.[1]

Ability Perimeters:

  • Punching Power: 40.6 t.[1]
  • Kicking Power: 49.6 t.[1]
  • Maximum Jump Height: 64.8 m.[1]
  • Maximum Running Speed: 100 m. per 1.4 sec.[1]

Bikaiser (バイカイザー Baikaizā) is the fusion of Kaiser and Kaiser Reverse, accessed when both Kaisers transform together.

Appearances: Heisei Generations FINAL: Build & Ex-Aid with Legend Riders



Behind the Scenes


The World of Ex-Aid's Kaisei Mogami is played by Kenji Ohtsuki (大槻 ケンヂ Ōtsuki Kenji).


In the script of Kamen Rider Heisei Generations FINAL: Build & Ex-Aid with Legend Riders, Kaisei Mogami's form was dubbed the R Kaiser (アールカイザー Āru Kaizā, Right Kaiser), equal to the L Kaiser.[2]




Sento Kiryu (Takumi Katsuragi) - Ryuga Banjo - Kazumi Sawatari - Gentoku Himuro - Evolto - Nariaki Utsumi - Shinobu Katsuragi
Movie-exclusive: Kengo Ino - Killbus - Keiji Uraga
Transformation Gear
Fullbottles - Build Driver - Transteam Gun - (Great) Cross-Z Dragon - Sclashjellies - Sclash Driver - Hazard Trigger - Nebulasteam Gun - Cross-Z Magma Knuckle - Evol-Driver - Evol-Trigger - Grease Blizzard Knuckle - Killbuspider - Grease Perfect Kingdom
Drill Crusher - Hawk Gatlinger - 4Koma Ninpoutou - Kaizoku Hassyar - Fullbottle Buster - Steam Blade - Beat Closer - Twin Breaker - Muscle Glove - Solstall Wings - Giant Scratcher - Space Ride Arm - Spine Knuckle - Long Range Cleaner - Trash Converter - Gold Lio Gauntlet - Multi Deluge Gun
Pandora Box - Halfbodies - Fullbottle Holder - Build Phone
Vortex Finish - Hazard Level - Project Build - Sky Wall - Nebula Gas
nascita: Misora Isurugi - Soichi Isurugi - Sawa Takigawa - Kazumi Sawatari - Gentoku Himuro
Kamen Riders: Eiji Hino - Gentaro Kisaragi - Kouta Kazuraba - Takeru Tenkuji - Emu Hojo - Hiiro Kagami - Taiga Hanaya - Kiriya Kujo - Kuroto Dan - Parado - Sougo Tokiwa - Geiz Myokoin - Tsukuyomi
Prime Ministers: Taizan Himuro (Touto) - Yoshiko Tajimi (Hokuto) - Masakuni Mido (Seito)
Namba Heavy Industries Ltd.: Juzaburo Namba - Nariaki Utsumi - Haruhiko Wanibuchi - Guardian
Hell Bro's: Fu Washio - Rai Washio - Yoshikazu Takahashi - Norio Matsui
Aliens: Vernage
Gentoku Himuro - Evolto - Nariaki Utsumi - Takumi Katsuragi - Shingo Kuwata - Eita Kawai - Yoshikazu Takahashi - Norio Matsui
Touto: Needle Smash - Strong Smash - Burn Smash - Flying Smash - Mirage Smash - Square Smash - Press Smash - Ice Smash - Stretch Smash
Hokuto: Castle Hard Smash - Stag Hard Smash - Owl Hard Smash
Kaiser: Kaisei Mogami (World of Ex-Aid)
Kengo Ino - Ryoka Saiga - Mitsuomi Gobara - Evolto - Killbus
Keiji Uraga - Simon Marcus (Phantom Crusher)
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