Michal Minato

Michal Minato (湊 ミハル) is a Kamen Rider from the future who originally became the heroic Kamen Rider Aqua (仮面ライダーアクア) and later Kamen Rider Poseidon (仮面ライダーポセイドン) whose Core Medals took control of him. He is also the movie-exclusive Rider(s) who appeared in the OOO section of the Movie War Mega Max film.

History
Michal is a Kamen Rider from 40 years in the future. At an unknown time he gained the Aqua Driver and the Aqua Miraider to fight monsters that appeared in his time. Michal is timid and feels he is too weak to be a Rider in the first place. He ironically couldn't be Aqua at first because he was afraid of water. Receiving the Poseidon Driver from the elderly Kosei Kougami, Kougami believes that the Poseidon Driver can help Michal overcome his timidness and fear, and grant him more power. However this proved futile, and even as Poseidon, Michal couldn't win against the creatures of his time, lost, and Michal was knocked out of transformation. However, just as he was about to give up, the black hole that was created by Kiyoto Maki's death appears, and the Core Medals and Cell Medals from the past entered his body, resulting in a Greeed forming inside the Poseidon Medals. This new Greeed develops an intense desire to fight, and Michal is almost instantly overwhelmed by the new being. With Michal's personality subdued, Kamen Rider Poseidon fights in their home time period for a brief while, but after a time anomaly forms as a result of a meteor containing SOLU crashing into the ocean in the present day, the Poseidon entity sees it's chance and dives through, heading off to fight the Kamen Riders of the past.

It arrives in the era of Kamen Rider OOO, and easily overwhelms a small troop of Kougami's soldiers, but is quickly intercepted by Ankh and Eiji Hino, who take some of his Cores in order to fight back. Poseidon flees to recuperate. Without the extra Cores to stabilize him, Michal is gaining control. Eiji confronts the dark Rider, and suppresses the Greeed's personality, but it soon resurfaces. After Kamen Rider Poseidon loses more of the Core Medals in his body to Eiji and Ankh, the Greeed splits apart with Michal, gaining his own body in the form of Kamen Rider Poseidon. Michal profusely apologizes to Eiji and Ankh, telling his story to the two to Ankh's amusement. But Eiji tells him the true meaning of being a Kamen Rider, having the courage to see tomorrow no matter what it may bring. Just as the battle with Poseidon seems bleak, Michal arrives on his Aqua Miraider, and realizes that what he needed was not power, but courage, and transforms into the heroic Kamen Rider Aqua. He turns the tides quickly, and uses his Oceanic Break together with OOOs' Prominence Drop to finish Poseidon off. He thanks OOO for all he has done for him, then leaps through the time anomaly on the Aqua Miraider, to protect his time as a Kamen Rider.

During the final battle against Kannagi's forces, he returns to the present and gives Eiji the Super Core Medals. He then dashes off to aid the Seven Legendary Riders in battle against the eight Dummy Inhumanoids, going up against a recreation of Greeed Kazari and destroying it with his Aqua Vortex.

Portrayal
Michal Minato was portrayed by Atsushi Arai (荒井　敦史). As Kamen Rider Aqua, his suit actor was Eitoku (永徳) while his suit actor as Kamen Rider Poseidon was Jun Watanabe (渡辺 淳).