Hyōgo Otoo founded and manages the Wagnaria family restaurant but entrusts most daily operations to Kyouko Shirafuji. This allows him to dedicate significant time to searching for his missing wife, Haruna Otoo. Haruna possesses a disastrous directional sense; she vanished during a shopping trip and has since navigated unconventional routes like sewer lines. Hyōgo sporadically returns to Wagnaria, often bringing unusual souvenirs like foreign candy, masks, or even individuals met during his travels. He recruited Aoi Yamada after hearing her fabricated story of parental loss.

Hyōgo maintains a consistently patient and kind demeanor, rarely displaying anger even in difficult situations. He tolerates Aoi Yamada's persistent pleas for adoption due to her view of him as an ideal father, though he maintains appropriate boundaries given his marriage. His devotion to Haruna remains his core motivation. His presence is often faint or "air-like," a trait Souta Takanashi notes prevents Mahiru Inami from perceiving him as a threat.

His relationship with Kyouko Shirafuji involves mutual reliance; he depends on her for restaurant management despite her minimal work ethic, while she primarily sees him as a source of regional food souvenirs. Interactions with Yachiyo Todoroki carry danger, as she threatens him with a katana over delivering food to Kyouko. However, Yachiyo also feels guilt for failing to prevent Haruna's disappearances.

A significant development occurs when Aoi Yamada facilitates Haruna's return to Wagnaria alongside Kikuno Yamada, leading to a heartfelt reunion. Despite this, Haruna's tendency to wander persists, requiring ongoing searches. Aoi Yamada remains uniquely capable of finding her during these episodes, fostering a bond where Aoi views Haruna as a maternal figure.