A former street fighter named Takeshi Yoroi now works as a private investigator. When three prototype Polymar Suits developed jointly by the Metropolitan Police Department and the Ministry of Defense are stolen, criminals begin using their powerful abilities to commit increasingly brazen crimes. The suits were originally designed for solo infiltration and combat, but development was halted years earlier by a police superintendent who feared the destructive power they represented. The newly inaugurated superintendent Akihito Yashiro resumes the project, but only the original complete red Polymar Suit can counter the stolen versions. This suit has a unique security feature it can only be activated by a specific voice dialogue code, and Takeshi is unknowingly the only person in the world who possesses that voice.

Takeshi is recruited to assist in the investigation by criminal director Tokita. He initially refuses, carrying a deep distrust of police, but agrees after being drawn in by Rei Hieda, a researcher involved with the Polymar Suits. Takeshi works alongside his partner Joichi Kuruma, a gentle and somewhat inexperienced detective, while Teru Nanba, the self-proclaimed detective assistant who is also the landlord of their office building, helps with their cases. As the investigation unfolds, Takeshi activates the Polymar Suit and witnesses its terrifying power firsthand. The suit enhances his already formidable martial arts skills, particularly the destructive force of his signature Hurricane fist, transforming him into an invincible red-suited hero. He can maintain the transformation for 46 minutes and one second before the suit reverts.

The stolen suits are wielded by a collection of formidable adversaries including Polymar Artemis, Polymar Leg Custom, Polymar Arm Custom, and Polymar Titan, each modified for specific combat roles. As Takeshi battles these enemies, the investigation reveals deeper layers of betrayal, past secrets, and a vast conspiracy that threatens to overthrow the established order. The red Polymar Suit itself holds a hidden mystery that becomes central to understanding the true nature of the conflict. Throughout the story, Takeshi must reconcile his hatred for authority with the responsibility that comes with his immense power, ultimately facing a choice that will determine what justice truly means.