Live action TV
Description
Jun Shibaura is a third-year university student attending Meirin University, where he studies computers and programming as a member of the Matrix Netgame Club. He is the son of a wealthy company president, a fact that contributes to his sense of entitlement and superiority. Shibaura is a skilled hacker and expert gamer who views the world through the lens of gameplay, treating real-life situations as extensions of the video games he creates and plays.

Shibaura is characterized by a profound sense of arrogance and a self-centered worldview. He takes pleasure in flaunting his intelligence and resourcefulness, believing these qualities place him above others. He has no moral qualms about toying with human lives, which he considers nothing more than entertainment. This detachment allows him to manipulate people without guilt, orchestrating dangerous situations for his own amusement. However, his arrogance is also his greatest weakness, as he consistently underestimates those he seeks to control, a miscalculation that ultimately proves fatal.

His primary motivation for entering the Rider Fight is simply to win. He does not harbor any noble goals or personal vendettas; instead, he sees the entire conflict as just another game to be conquered. This gamified perspective extends beyond the Rider Fight itself, as he creates a deadly competition among his own club members, forcing them to fight to the death while he observes from the shadows, treating their suffering as part of his entertainment.

Within the story, Shibaura serves as an antagonist who uses his technological expertise to gain leverage over others. He successfully hacks into the ORE Journal computer system, steals subscriber data, and uses this to blackmail his way into becoming head of the company. He also steals Kamen Rider Ryuki's Dragreder card, temporarily crippling his opponent's abilities. Shibaura goes so far as to kidnap Yui Kanzaki, using her as bait to force multiple Riders into a confrontation he calls a "Rider party". His father, concerned about his son's legal troubles, retains the lawyer Shuichi Kitaoka to bail him out of police custody, creating an ironic connection between Shibaura and another Rider whose identity he later discovers.

His key relationships are defined by manipulation and conflict. He considers Shinji Kido, Kamen Rider Ryuki, to be useless and enjoys tormenting him. He dismisses Ren Akiyama, Kamen Rider Knight, as a coward. He is impressed by the dangerous and sadistic nature of Takeshi Asakura, Kamen Rider Ouja, and believes he can control Asakura as part of his larger game. This belief in his own ability to manipulate the unmanageable proves to be his undoing. During a chaotic battle involving multiple Riders, Asakura uses Shibaura as a shield against Kamen Rider Zolda's Final Vent attack and then kills him directly. His Mirror Monster partner, Metalgelas, is enraged by his master's death and attacks Ouja, only to be claimed by him as well. Unlike some other Riders, Shibaura does not reappear in the story's epilogue after the timeline is reset.

As Kamen Rider Gai, Shibaura possesses notable combat abilities. His Rider form stands 195 centimeters tall and weighs 100 kilograms. His punching and kicking power are measured at 15 tons each, and he can jump 20 meters into the air. He wields the Metalvisor on his left shoulder, which allows him to activate his Advent Cards. His Strike Vent summons the Metalhorn, a powerful gauntlet based on Metalgelas's head. His Final Vent, called Heavy Pressure, has an attack power of 250 tons, making it a devastating finishing move where he latches onto Metalgelas and charges at the enemy. He also possesses a Confine Vent card that can nullify other Riders' Advent Card effects, demonstrating his tactical approach to combat. His Mirror Monster, Metalgelas, is a rhinoceros-like creature with a metallic hide capable of crushing cars, moving at extreme speeds to support Gai in battle. Despite these impressive parameters, he lacks any defensive weapons and is considered one of the least agile among the Riders.