Ayumu Goriki is a 41-year-old physician running his own Gouriki Medical Clinic. He became the primary doctor for Hiroshi Odokawa three years ago after encountering him as a taxi passenger. Goriki exhibits a calm, serious, and intelligent demeanor, consistently showing concern for his patients' well-being, particularly Odokawa's chronic insomnia and psychological state. He maintains a stable family life, being married with children.

Goriki's medical assessments extend beyond physical health. Observing Odokawa's unusual abilities—instantly recognizing individuals from poor photos and recalling obscure details about patrons—led Goriki to hypothesize his patient might experience synesthesia, where one sense triggers another, explaining his perceptiveness. Goriki later discovered medication discrepancies at his clinic, suspecting theft. Evidence implicated nurse Miho Shirakawa, prompting him to consider closing the clinic to avoid police involvement and protect her, demonstrating a protective stance toward his staff despite potential legal consequences.

His investigation into Odokawa intensified upon learning of his patient's childhood trauma: a fatal accident involving his parents during elementary school. Goriki contacted Odokawa's former physician and examined a memory notebook from that time. This research yielded a breakthrough diagnosis: Odokawa suffers from visual agnosia, causing him to perceive humans as anthropomorphic animals, explaining his descriptions of people as animals. Their consultations occasionally reveal Goriki's dry humor, like their recurring exchange about musician Bruce Springsteen.

Following the anime series, Goriki appears in the film continuation, which depicts ongoing developments after the original storyline. His role persists as Odokawa's physician during the resolution of the missing girl case and its aftermath.