Kanzaki is a city located in Saga Prefecture, Japan. As of February 28, 2017, the city has an estimated population of 31,981 and a populatio…Kanzaki is a city located in Saga Prefecture, Japan. As of February 28, 2017, the city has an estimated population of 31,981 and a population density of 260 persons per km². The total area is 125.01 km².