Live action TV
Description
Jun Shibaura is a participant in the Rider Battle who transforms into Kamen Rider Gai. He is a 21-year-old second-year college student from a wealthy family, as his father is a successful company president, and he is known for his prodigious skill as a computer programmer and hacker. Unlike most other Riders who receive their powers from the mysterious Advent Cards, Jun takes an unconventional approach by using his technical expertise to create his own artificial Rider system, allowing him to enter the conflict on his own terms. His appearance as Kamen Rider Gai features a black and grey armored suit with a menacing, rhinoceros-themed design.

Jun possesses a deeply arrogant, cold, and calculating personality. He is characterized as a sociopath with a cruel, entitled, and obnoxious demeanor who treats the lives of others as pieces in a game for his own amusement. He has no regard for human life and enjoys toying with people, dominating their minds, and creating violent games that push others to harm each other. His primary motivation for joining the Rider War is not a noble wish or desperate need, but simply for the pleasure of playing what he views as another game, seeking recognition and revenge against a society he feels has marginalized him.

In the story, Jun first draws attention by creating a violent online video game that influences his classmates to fight each other in real life, an incident that brings him into conflict with Shinji Kido. He later hacks the ORE Journal news company, blackmailing them to make himself the temporary editor-in-chief in an attempt to spread his violent game across the country. As Kamen Rider Gai, he provokes other Riders to fight, steals Shinji’s important Advent Card, and even kidnaps Yui Kanzaki to force a major battle between the participants. His primary enemies and rivals include Shinji Kido (Kamen Rider Ryuki), Ren Akiyama (Kamen Rider Knight), and the particularly vicious Takeshi Asakura (Kamen Rider Ouja), whom he attempts to manipulate.

Throughout his arc, Jun shows very little signs of redemption or internal conflict, remaining a largely static antagonist driven by his thirst for control and entertainment. His character arc ends when his attempt to use Ouja backfires, resulting in Ouja attacking and mortally wounding him. In his dying moments, Jun ironically complains that Ouja ruined his game, refusing to take responsibility for his own actions. His story serves as a cautionary tale about the dangers of unchecked ambition and the misuse of intelligence.

As Kamen Rider Gai, Jun possesses impressive but artificial abilities. His Rider form has a punching and kicking power of 15 tons, a maximum jump height of 20 meters, and can run 100 meters in 5 seconds. His senses are heightened, allowing him to see up to 8 kilometers and hear up to 10 kilometers away. Jun fights using his Contract Monster, Metalgelas, a powerful rhinoceros-like creature with a metallic hide. Through his Metal Visor, he can use Advent Cards to summon Metalgelas, arm himself with the Metal Horn gauntlet weapon, and employ his finisher, Heavy Pressure, where Metalgelas charges at the enemy with Gai acting as a lance. He is particularly known for using the Confine Vent card, a rare and strategic ability that nullifies the weapons or attacks of other Riders, showcasing his tactical and cunning nature in combat.