Okō is the chief assistant of Shugo Hell (Mortal Hell), managing matters concerning relationships and interpersonal entanglements among the deceased. She sports a distinctive appearance: pastel blue hair featuring two small black horns and a pink lily accessory. Her typical outfit is a purple kimono adorned with green and yellow triangular borders, worn with pink geta shoes. Live female pink snakes are incorporated into her obi (sash). She stands 168 centimeters tall.

Universally amicable, Okō maintains friendly relationships with nearly all underworld inhabitants. She consistently displays politeness and a quiet demeanor. However, her occasional commentary reveals a perceptive and incisive nature, often delivered with a composed smile, creating a defining contrast. She attracts significant romantic attention from several male characters, including prominent admirer Karauri. Despite this admiration, she reciprocates no romantic interest towards anyone, maintaining strictly platonic relationships. She has stated that personality would be her foremost priority if romantic considerations ever arose.

Within Shugo Hell, her responsibilities involve administrative duties related to adjudicating and managing souls entangled in complex interpersonal circumstances. She interacts professionally with other underworld figures, such as Hozuki and his subordinates, within Hell's bureaucratic structure. Her portrayal remains consistent in function and demeanor throughout depicted events. Her connection to snakes extends beyond adornment, reflecting a thematic association with her domain.