Shiro Mizuki

Shiro Mizuki (水城 史朗) is the human alter-ego of Kamen Rider G4 (仮面ライダーG4), a Rider who only appeared in Kamen Rider Agito: Project G4.

Overview
He was one of the military personnel guarding the GA psychic educational facility during the time it was attacked by the Formica Pedes. Though he would survive the ordeal, he would be left a jaded man.

With his pride as a soldier shattered, Mizuki began living as one who would embrace death as the true means of becoming stronger. He would eventually volunteer as the operator for the G4 exo-suit and, as fate would have it, clash with G3-X operator Hikawa, to put their ideals to the test on the battlefield. But throughout the course of the battle, the G4 begins to suffer malfunctions.

But despite this, Mizuki refused to surrender. In the end, Mizuki would succumb to the strain placed upon him by the G4 and die. The G4's AI attempted to rise and continue the battle, but was destroyed by Hikawa.

Decade

 * G4's chip appears in Kamen Rider Decade series. The chip was found in Shouichi Ashikawa's old locker by Daiki Kaito. The chip, however, was destroyed by Toko Yashiro.
 * In Kamen Rider × Kamen Rider W & Decade: Movie War 2010, G4's Gigant was used by Decade, through "Attack Ride: Gigant" card which means G4 may be carded by Decade.
 * G4 makes another appearance in Kamen Rider × Kamen Rider × Kamen Rider The Movie: Cho Den-O Trilogy Episode Yellow: Treasure de End Pirates, he was summon by Kamen Rider Diend Complete Form with "Gekijouban" (translate is Movie) Attack Ride Card alongside with other 7 Riders: Kamen Rider Ryuga, Kamen Rider Orga, Kamen Rider Glaive, Kamen Rider Kabuki, Kamen Rider Caucasus, Kamen Rider Arc, and Kamen Rider Skull (the last of whom is the Dummy Dopant in disguise).

Kamen Rider Agito video game

 * In the Kamen Rider Agito game for the Playstation, while G3/G3-X has limited fighting time and will instantly K.O after the time is over, G4 doesn't suffer that limitation, possibly because G4 is a more advanced version and has successfully eliminated the weakness of G3/G3-X system.

Kamen Rider G4
Kamen Rider G4 was an upgraded version of the G3 system conceptualized by Sumiko Ozawa from the G3-X model. However, the G4 was deemed far too dangerous for use, so Ozawa never included the adjustments in the design schematics. But, Risako Fukami would steal the plans and construct the G4 System herself, adding a Prediction System to improve the AI and make the G4 the most powerful weapon on Earth. Unlike earlier G-Series of Kamen Riders motif based on Kuuga, G4's motif was based on Kamen Rider Agito.
 * Head height: 198 centimeters (6ft 4in)
 * Base weight: 150 kilograms (330.6lbs)
 * Ability perimeters
 * Punching power: 4t
 * Kicking power: 13t
 * Maximum jump height: 25m (82ft)
 * Maximum running speed: 100m/7.5s (328ft/3.5sec)
 * Vision: 15 km approx. (9.3 miles)
 * Hearing: 15 km approx. (9.3 miles)
 * Defense Rating: 8

Physically, G4 would reflect Agito's Burning Form, but the horns on G4's helmet resemble Agito's crest horns (unopened) from his basic Ground Form. And fittingly, being a Dark Rider, the colors on G4's eyes (blue) are also colors that happen to contradict Agito's Eyes (yellow); even G3-X's eyes (a much more red shade) also contradict G4's.

However, despite G4's motif being based on Agito instead of Kuuga, G4 still has design elements resembling parts of Kuuga's Standard & Rising Forms (shoulders and trim, although Agito's Burning Form is also shown to have a trim), as well as his Ultimate form (legs, body, arms, and G4's black and yellow color palette at the torso.)

Equipment

 * GM-01 R4 - A modified version of the Kamen Rider G3's GM-01 "Scorpion"; a modular magnum pistol, stored on right hip, hand-carried in use.
 * "Gigant" - A shoulder-mounted missile launcher, mounted over the right shoulder when in use. Used as a finisher.

Rider Cards

 * Kamen Ride: G4: A Rider Card containing the power of Kamen Rider G4, possessed by Kamen Rider Diend. It one of the eight cards used by Diend Complete Form. It summons Kamen Rider G4.
 * Attack Ride: Gigant: The Gigant Attack Ride Card is used by Decade to summon Kamen Rider G4's Gigant to attack enemies. Used to defeat Kamen Rider J.

Portrayal
Shiro Mizuki was portrayed by Ryo Karato (唐渡 亮). As Kamen Rider G4, his suit actor was Jiro Okamoto (岡元 次郎).

Rider notes

 * In terms of the users (Hikawa and Mizuki), the utilization of the G3-X and the G4 exo-suit near the end of Project G4 is reminiscent of the final battle between Kuuga Ultimate Form and N-Daguva-Zeba.
 * Shiro Mizuki and N-Daguva-Zeba also happen to be more willing to die (and end up doing so) for their motives, with Mizuki fighting for his ideals in life, and N-Daguva-Zeba fighting to accomplish either one of his goals.
 * Unlike the majority of Heisei Dark Riders who are based on the Primary Rider in their respective series, G4 is the only one based on the Secondary Rider.
 * Though, by extension, this also means he's based on the Primary Rider from the previous series.