Kawaguchi is a city located in Saitama Prefecture, Japan. As of 1 January 2021, the city had an estimated population of 607,373 in 293,582 households and a population density of 9800 persons per km². The total area of the city is 61.95 square kilometres. It is the Greater Tokyo Area's 8th most populated city, and second largest in Saitama Prefecture, after eponymous Saitama.