Kaisei Mogami

Kaisei Mogami (最上魁星) is a former researcher of the Touto Institute of Advanced Matter Physics and one of the main antagonists of Kamen Rider Heisei Generations FINAL: Build & Ex-Aid with Legend Riders.

Character History
He was a researcher of Touto Institute of Advanced Matter Physics, who devised Kaiser system with Takumi Katsuragi. He also build cross-dimensional machine called Enigma together with him.

Post-mortem
Facing a new model Bi-Kaiser, Sento Kiryu initially believed that Kaisei Mogami had returned, bewildered as to how he could have survived. When he defeated the Bi-Kaiser, however, he found the true identity to be an innocent test subject whom had been exposed to Nebula Gas. Infact, the late Mogami's Kaiser System had been updated by Nariaki Utsumi on behalf of Blood Stalk and Namba Heavy Industries Ltd., and the prototype's battle with Build allowed him to finalize the new Hell Bros.

Sento was again reminded of the unification of the two Kaisei Mogamis into Bi-Kaiser when he witnessed Fu Washio transform into Hell Bros.

Personality
He is a violent, evil scientist bent on annihilating all humans.

Devices

 * Nebula Steam Gun - Transformation device and sidearm
 * Unknown blue Gear - Transformation trinket

Portrayal
He is played by Kenji Ohtsuki (大槻 ケンヂ).

Appearances

 * Icon-build.png Kamen Rider Build
 * Icon-exaid.png Kamen Rider Heisei Generations FINAL: Build & Ex-Aid with Legend Riders
 * Kamen Rider Build: Raising the Hazard Level ~7 Best Matches~ Next Chapter
 * Episode 23: The Phantom of the West
 * Episode 27: The Counterattack Hero