Usa is a city in Ōita Prefecture, Japan. As of 30 November 2023, it had an estimated population of 52,808 living in 26,026 households, with a population density of 120 persons per square kilometre. The city covers a total area of 439.05 square kilometres (169.52 square miles).
Usa is best known for Usa Jingū, which is the head shrine of all 40,000 Hachiman shrines across Japan. This status makes the city a focal point of Hachiman worship nationwide.