Higeoyaji, also called Shunsaku Ban, traces his roots to a caricature by Osamu Tezuka’s middle school classmate portraying the classmate’s father, not Tezuka’s original invention. Tezuka first adapted this design in his 1943 amateur debut "Old Man Detective." The nickname "Mustached Old Man" highlights his signature thick, U-shaped mustache, portly build, and balding head.

In "The Three-eyed One," he operates Tokyo’s Rairaiken ramen shop while acting as a close confidant and intermittent guardian to Dr. Kenmochi, adoptive father of protagonist Hosuke Sharaku. Dr. Kenmochi regularly leaves Sharaku in Higeoyaji’s care, where the boy’s distractibility and clumsiness disrupt the shop. Despite this, Higeoyaji shows unwavering patience and sympathy, shielding Sharaku from bullies or danger. His gruff, short-tempered exterior masks a fiercely protective and warm-hearted core.

Across Tezuka’s "Star System," he consistently embodies a loud, justice-obsessed middle-aged man—outspoken, quick to erupt in anger, and driven by righteousness, often resorting to physical confrontation. Though prone to overreactions and abrasive language, his loyalty and dedication to defending others remain unshakable.

Beyond "The Three-eyed One," Higeoyaji appears in diverse Tezuka roles: private detective, teacher, sushi chef, pickpocket, and father seeking reconciliation with his son. Younger versions emerge in "The Green Cat" (sporting jet-black hair sans mustache) and "Atom: The Beginning" (as a 15-year-old science enthusiast). Regardless of era or occupation, his combustible temper, ironclad sense of justice, and occasional clumsiness define him.