Kyouji Murakami is the acting chief of the Smart Brain corporation in the alternate world depicted in the film. As the primary antagonist, he is a high-ranking Orphnoch known as the Rose Orphnoch, a being with the nature of a rose flower. In this timeline, his leadership has been instrumental in Smart Brain's near-total domination of the world, with roughly ninety percent of the population transformed into Orphnochs.

At the time of the film's events, Murakami is in a grotesque yet formidable state, existing only as a living head kept alive in a specialized tank, attended to by his subordinate, Smart Lady. Despite this condition, he remains the calculating and ruthless mastermind behind Smart Brain's operations. His primary goal is the complete extinction of the surviving human race, viewing them as having no place on the new world order. To achieve this, he oversees the deployment of the powerful Emperor Belts, advanced Rider Gears designed to be used exclusively by Orphnochs. He identifies the Horse Orphnoch, Yuji Kiba, as the ideal candidate for one of these belts, the Orga Driver, and uses a disguised Smart Lady to manipulate him emotionally.

Murakami's role in the story is to act as the orchestrator of humanity's final defeat. He commands his forces, including the Riotroopers and a loyal Orphnoch named Leo who transforms into Kamen Rider Psyga, to capture Mari Sonoda, the symbolic leader of the human resistance. He also unleashes the massive Elasmotherium Orphnoch as a weapon of mass destruction to eliminate his enemies. His relationship with his subordinates is purely utilitarian. He discards Leo when he fails and ultimately suffers a betrayal from Smart Lady, who crushes his tank on the orders of the company's higher executives after his repeated failures to eliminate Kamen Rider Faiz.

As the Rose Orphnoch, Murakami possesses several notable abilities. He can generate and expel rose petals from his head, which can serve as a smokescreen or a teleportation mechanism, allowing him to dissipate and reappear elsewhere. He can also channel blue flames from his hands to create fireballs for combat, an ability he can utilize even in his human form. While he never transforms into his full Orphnoch form in the film, his mental fortitude and strategic planning serve as his primary weapons. His development is static; he remains an unwavering symbol of Orphnoch supremacy, whose confidence is only broken by his ultimate execution for incompetence at the film's climax.