J, also referred to as Mr. J, is the human identity of the Crocodile Orphnoch, a character who appears as a notable antagonist. He is a young man of 26 years, characterized by a strong, muscular build and a generally silent demeanor. As his name suggests, his Orphnoch form is based on a crocodile, granting him formidable physical power and unique abilities that set him apart from standard members of his kind.

A member of the elite Orphnoch group known as Lucky Clover, J operates under the orders of Smart Brain, the corporation that serves as a front for Orphnoch activities. He is often seen in the company of his beloved pet chihuahua, a small dog named Chaco. This relationship is central to his personality; despite his menacing appearance and fearsome reputation as an executioner, J displays a gentle and caring side when it comes to his pet. His deep affection for Chaco is one of his few emotional vulnerabilities and a primary motivator for his actions. When he is not on a mission, he can be found at the Lucky Clover bar, where his drink of choice is draft beer.

J's primary motivation throughout his appearance is not born of personal malice or ambition, but rather a mixture of duty and coercion. Initially, he is dispatched by his superiors to eliminate the Kamen Riders, particularly Faiz, and to retrieve the Rider Gear. However, after he suffers crushing defeats, his willingness to continue the pursuit wanes. His superiors, namely the Smart Brain executive Murakami, exploit his bond with his pet to keep him in line, threatening both to label him a traitor and to harm Chaco if he fails to complete his mission. This coercion forces a reluctant J to continue fighting even when he would rather stop, highlighting a tragic aspect of his character as someone bound to a violent path against his better judgment.

In the story, J serves as the first member of Lucky Clover to be sent directly after the protagonists. He is a recurring physical threat whose unique ability to resurrect makes him a persistent and escalating danger. Unlike other Orphnochs who die permanently when defeated, J possesses the rare and distinctive power of having three lives. Each time he is killed, he does not simply vanish; instead, his body reconstitutes from a pile of ash, and he returns in a new, more powerful form. This process, which can occur twice before his final death, makes him a relentless foe who grows stronger with each encounter. Initially appearing in his Fight Form, he revives as his Strength Form and finally as his Rampage Form, each stage boasting increased durability, strength, and new weaponry.

Regarding key relationships, J's most significant bond is with his pet chihuahua, Chaco. This connection humanizes him and serves as his primary point of interaction with other characters, such as when he shows genuine kindness to a young woman who looks after the dog. His relationship with his superiors in Lucky Clover and Smart Brain is one of a tool to his masters; he is valued for his power but is ultimately disposable. He interacts with other Orphnoch members as a colleague, but his silent nature suggests a degree of isolation. His central antagonistic relationships are with the Kamen Riders, including Faiz and Kaixa, whose different users defeat him across his three lives.

In terms of development, J's arc is a descent from a confident enforcer to a reluctant pawn, culminating in his final, permanent demise. After being killed twice by two different users of the Kaixa Gear, he is left with his final life and a stark understanding of his own mortality. Despite a clear reluctance to fight again, the threat to his dog forces him into one last battle. He confronts Faiz in his most powerful Rampage Form, proving himself a formidable opponent who can even deflect Faiz's signature finisher. Ultimately, he is defeated by a powerful counterattack, and his body finally turns to ash for good. After his death, Chaco is taken in by a woman named Keiko Kurata, providing a small, bittersweet resolution to his story.

The Crocodile Orphnoch possesses several notable abilities. His crocodile hide provides immense natural armor, making him highly resistant to bullets and physical attacks. His physical strength is enormous, with his punching force measured at several tons. In his various forms, he wields distinct weapons: in Fight Form, he uses crocodile-tooth shields on his arms; in Strength Form, he uses a large blade resembling a crocodile's jaw; and in his final Rampage Form, he wields a massive, heavy sword capable of shattering rock. He can also use a tendril from his body to destroy human hearts and create other Orphnochs. However, his most defining power remains his ability to be reborn twice, each time with enhanced capabilities, making him a unique and memorable adversary whose threat level escalates with every encounter.