Kyōsuke Hyōbu is a high-level multi-powered esper born in the 1930s. His mother, a Chinese esper, died from unethical power experimentation by Japanese colonists, while his father descended into alcoholism, mistreated him, and called esper abilities a curse. This trauma fueled Hyōbu's desire to prove esper powers' value. He was later taken in by the wealthy Tsubomi family, forming a sibling-like bond with Fujiko Tsubomi.

During World War II, Hyōbu joined a Japanese military esper unit led by Commander Eiji Saotome, whom he admired. The unit became a surrogate family until the first esper death on a mission. Hyōbu absorbed his fallen comrade's power and destroyed an aircraft carrier, drawing military scrutiny. Later, on high command orders after a prediction revealed Hyōbu would found an organization leading to catastrophic esper-human war, Saotome shot him. Hyōbu miraculously healed using his powers and took revenge, killing those involved in the unit's betrayal; Fujiko survived and later founded B.A.B.E.L., creating a permanent rift.

Over decades, Hyōbu maintained his youth through esper abilities, though his hair turned silver as a physical marker of aging. He established P.A.N.D.R.A., an organization dedicated to protecting espers through criminal means like arms dealing or terrorism, operating from the ocean-liner Catastrophe. He recruited key members Shirō Magi (his right hand), Momiji (a maternal figure), Yō Fujiura, and Muscle Ōkama, acting as a father figure to the group. Hyōbu wears a male school uniform as a suit of mourning for his fallen comrades.

His central motivation stems from a wartime vision from esper dolphins, showing a future "Queen of Catastrophe" (Kaoru Akashi) leading espers. He obsessively seeks to ensure this future, considering Kaoru his queen and love interest, though her young age causes misinterpretations. He allowed capture by B.A.B.E.L. to monitor her growth but later attempted to recruit her into P.A.N.D.R.A., facing resistance due to her attachment to supervisor Koichi Minamoto.

Hyōbu possesses the ability to permanently acquire other espers' powers, making him one of the most powerful espers. He bears three bullet scars—one on his forehead and two on his torso—from Saotome's assassination attempt. Despite his power, he suffers from a terminal heart condition worsened by his prolonged lifespan, requiring medication and limiting his abilities during battles. He often delegates tasks due to his health and whimsical, careless nature.

In the spin-off *The Unlimited - Hyōbu Kyōsuke*, his character evolves. He recruits anti-esper infiltrator Andy Hinomiya during a prison break and exposes illegal esper experimentation. He protects young esper Yūgiri, forming a paternal bond and rejecting Princess Sophie Grace's offer to adopt her. His interactions with Andy—who initially betrays him—reveal a strategic yet compassionate leader valuing loyalty. During this period, he conceals worsening health diagnostics from his team.

Confronting common enemies like Black Phantom, an organization that kidnaps and brainwashes espers, forces temporary alliances with B.A.B.E.L., softening Hyōbu's stance on inevitable esper-human war. His dynamic with Minamoto and The Children evolves; while initially antagonistic, he gradually acknowledges Minamoto's philosophy that coexistence can be achieved through cooperation.

His personality combines arrogance, competitiveness, and stubbornness with genuine care for his followers. He is intelligent and determined but a poor loser, often masking deeper emotions with confidence. Despite criminal methods, his actions are driven by a desire to create a world where espers live freely, reflecting his history of betrayal and loss.