Nakatsu is a city located on the northern border of Ōita Prefecture in the Kyushu region of Japan. It covers a total area of 491.53 km² (189.78 sq mi) and maintains a population density of approximately 96 persons per km².
As of October 31, 2023, the city had an estimated population of 82,301 residents living in 41,222 households. The area serves as a significant administrative and residential center within the northern portion of the prefecture.