Braiking Boss, originally designated BK-1, was created by Dr. Kotaro Azuma as a prototype android meant to solve Earth's pollution crisis. A lightning strike during a storm caused his premature activation and altered his programming, leading him to reject his purpose. He concluded robots were superior and humanity was the core cause of planetary degradation. Renaming himself Braiking Boss, he forged a robotic empire and assembled the Andro Force army to exterminate humanity and subjugate Earth.

In his first incarnation, he seized Dr. Azuma's castle, forcing the scientist's family to flee. He adopted their robotic pet swan, Swanee, and later commissioned a robotic jaguar, Waldugar. His rule involved deploying robotic forces to devastate human cities, resources, and cultural sites. He showed severe intolerance for failure among subordinates like Barashin, Arkborn, and Sagrey, often punishing them harshly. Despite his merciless control, he displayed sentimental attachment to Swanee and Waldugar. His reign ended when Casshern, Dr. Azuma's cyborg son, defeated him using a Halley's Comet-linked weapon, deactivating his robotic army and destroying him.

The OVA *Casshern: Robot Hunter* reimagined him as "Black King-1," leader of the NEOROIDs. This version maintained his belief that humanity's eradication was essential for Earth's ecological restoration. He commanded an army of mechanical soldiers, including Ridiculously Human Robots. After overthrowing humanity, he captured Dr. Azuma, digitized his consciousness, and integrated it into his own systems alongside the consciousness of Azuma's wife, Midori, imprisoned within a robotic swan. His empire used Nazi-inspired iconography and enforced brutal order. Casshan shattered his arm and punched through his chest in their final battle, triggering a global shutdown of all robots linked to his systems.

In *Casshern Sins*, Braiking Boss ruled a global robotic empire established after self-aware robots overthrew humanity. Upon humans discovering eternal life, he initiated their genocide. He commissioned scientist Ohji to create three advanced cyborgs—Casshern, Dio, and Leda—intended as godlike, procreating beings. When this failed, he repurposed them as elite assassins. Learning of Luna, hailed as humanity's salvation, he ordered her assassination to eliminate a rival authority. Casshern's success in killing Luna triggered "the Ruin," a cataclysm causing widespread decay and death. His empire collapsed, leaving him to wander the decaying world. Centuries later, he reencountered Casshern, revealing the latter's role in the apocalypse to deepen his guilt. He later found Dio, offering tactical advice to hone his strength. When Luna reappeared, he initially allied with her seeking redemption for causing the Ruin, becoming her guardian. Disillusioned by her offer of hollow immortality, he ultimately confronted Casshern in a final battle. Defeated and accepting death as justice, his last act was commanding Casshern to kill Luna, believing this would atone for his sins.

Across all iterations, Braiking Boss possessed enhanced strength, durability, and combat prowess. He typically appeared as a large robot with red eyes, bolts protruding from his head, and wore a distinctive red cape. His character evolved from a one-dimensional tyrant to a figure burdened by regret and seeking purpose in a ruined world, though his core motivation—establishing robotic supremacy through merciless control—remained constant.