Shiro Mizuki is the user of the G4 system to become Kamen Rider G4 and the main antagonist of the movie Kamen Rider Agito: Project G4.


Kamen Rider Agito: Project G4

Shiro Mizuki was one of the soldiers assigned under Risa Fukami, the captain of the GA division. Mizuki was assigned to guard the GA psychic educational facility shortly before it was by the Formica Pedes. Though he survived the attack, the experience would color his worldview and lead him to embrace death to become stronger

Mizuki eventually volunteered as a test subject for the G4 exo-suit, knowing fully of the possibility that it would kill its user. Mizuki soon became enemies with the G3-X operator, Makoto Hikawa, as he embraced death while Hikawa embraced life. The two eventually settled their differences in wordlview by fighting each other, but over the course of the battle the G4 system began malfunctioning. Mizuki refused to surrender, though he was ultimately killed by the strain of the system. Despite Mizuki's death, G4's AI attempted to continue fighting but it was destroyed by Hikawa.

Kamen Rider Decade

Kamen Rider G4 was one of the Riders who appeared in Natsumi Hikari's dream of the Rider War.

He later appears as one of the Kamen Riders who took part in the Rider War and fought Kamen Rider Decade.

Kamen Rider Zi-O

Kamen Rider G4 was one of the Riders summoned from another world by Another Decade to fight Zi-O and Geiz.



           Kamen Rider Agito Villains

OverLord of Darkness | El of the Water | El of the Wind | El of the Ground

Risa Fukami | Shiro Mizuki | Kaoru Kino

           Zi-O Logo Villains

Time Jackers
Uhr | Ora | Swartz | Tid

Another Riders
Another Build | Another Ex-Aid | Another Fourze | Another Faiz | Another Wizard | Another OOO | Another Double | Another Den-O | Another Kuuga | Another Gaim | Another Ghost | Another Shinobi | Another Quiz | Another Ryuga | Another Kikai | Another Zi-O | Another Blade | Another Agito | Another Ryuki | Another Hibiki | Another Kiva | Another Kabuto | Another Den-O II | Another Drive | Another Decade

Oma Zi-O's Army
Oma Zi-O | Woz | Kasshin | Dai Mazines

Future Riders
White Woz | Kamen Rider Ginga

Legendary Riders
Masato Kusaka | Kaito Kumon | Tsukasa Kadoya | Hajime Aikawa | Daiki Kaito | Shun Kageyama (Imposter) | Katsumi Daido

Another World Riders
Kamen Rider G4 | Kamen Rider Fuma | Kamen Rider Dark Ghost | Kamen Rider Rey | Kamen Rider Eternal | Kamen Rider Woz | Kamen Rider Yuuki

Kamen Rider Barlckxs | Kagen | Jogen | Woz | Kasshin

Tid's Army
Masquerade Dopants | Waste Yummies | Stardust Ninja Dustards | Elementary Inves | Ghouls | Elementary Inves | Low-Class Roidmudes | Chase | Gamma Commandos | Guardians | Hard Guardians

Swartz's Army
Monsters: Strong Smash Hazard | Mashin Chaser | Elementary Inves | Orion Zodiarts | Shika Inves | Utopia Dopant | N-Daguva-Zeba | Sagittarius Zodiarts | Gamedeus | Kamen Rider Evol
Footsoldiers: Guardians | Masquerade Dopants | Low-Class Roidmudes | Ghouls | Gamma Commandos | Bugster Virus

Waste Yummies | Gamma Commandos | Humanoise | Salis Worms | Gryllus Worm | Mole Imagin

Rider Time Shinobi
Niji no Hebi
Yaminin | Stardust Ninja Dustards

Rider Time Ryuki
Tatsuya Kano | Takeshi Asakura | Jun Shibaura | Ishihashi | Tozuka | Kamen Rider Odin

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