Inokawa-zeki is a high-ranking sumo wrestler at Raijin Stable, where he serves as the highest-ranked wrestler during Matsutaro Sakaguchi's early career. He is deeply dedicated to sumo and its traditions, consistently displaying a serious and disciplined demeanor. Inokawa-zeki acts as a benchmark for Matsutaro's abilities, decisively defeating him in a special training session in episode 5 of the 2014 anime adaptation. This encounter underscores the considerable gap between Matsutaro's raw strength and Inokawa-zeki's refined skill and experience.

Despite his traditionalist approach, Inokawa-zeki reveals a softer side through his care for a stray cat he regards as a good luck charm. He proves perceptive about the stable's internal dynamics, later acknowledging that Matsutaro's disruptive presence inadvertently strengthened and toughened all the Raijin wrestlers by creating a hectic environment.

His role extends beyond that of a mere opponent for the protagonist. Inokawa-zeki embodies the established order and professionalism within sumo, serving as a foil to Matsutaro's unrefined and carefree nature. While a clash between them is hinted at near the end of the 2014 series, the circumstances occurred outside an official match and provided an advantage to Matsutaro.