Saijō is a city in Ehime Prefecture, Japan. As of 1 September 2022, the city had an estimated population of 106,016 in 58,803 households an…Saijō is a city in Ehime Prefecture, Japan. As of 1 September 2022, the city had an estimated population of 106,016 in 58,803 households and a population density of 210 persons per km². The total area of the city is 509.98 square kilometres.