Okina Otogi, the gaunt, elderly head doctor of Nanbaka Prison, sports loosely tied gray hair, a wispy beard, and deep-set wrinkles framing a perpetual scowl. His bushy gray eyebrows accentuate a stern gaze, while his attire—a white lab coat with a red armband (emblazoned with a white heart), a khaki romper, and black flip-flops revealing painted black toenails—blends clinical authority with eccentricity. Red cross earrings and a kiseru pipe, rarely absent from his side, complete his distinctive look.

Brash and cantankerous, he habitually clashes with his wife, Kazari Otogi, over petty disputes like condiment choices, their volatile dynamic marked by public shouting matches. Yet they collaborate as creators and guardians of KAGU-8, an AI they treat as a daughter. Okina’s protectiveness borders on ferocity, with violent warnings to those endangering her.

Pragmatic in his prison role, he distrusts inmates but grants Nico unusual leeway near KAGU-8, deeming him harmless. Others, like Uno, Honey, or Trois, face stricter limits. His medical focus prioritizes surgery and consultations, reflecting both duty and passion.

The name "Okina" merges Japanese terms for "old man," "ten," and "righteousness," nodding to the folklore figure Taketori no Okina from *The Tale of the Princess Kaguya*. His pre-prison history and broader narrative contributions remain undocumented in existing media.