Usa is a city located in Ōita Prefecture, Japan. As of 30 November 2023, the city had an estimated population of 52,808 in 26026 households, and a population density of 120 persons per km2. The total area of the city is 439.05 km2. It is notable for Usa Jingū, the head shrine of all 40,000 Hachiman shrines across Japan.