Seto is a city in Aichi Prefecture, Japan. As of 1 October 2019, the city had an estimated population of 127,659 in 56,573 households, and a population density of 1,146 persons per km2. The total area was 111.40 square kilometres (43.01 sq mi).

Aichi Prefecture is a prefecture of Japan located in the Chūbu region of Honshū. Aichi Prefecture has a population of 7,552,873 and a geographic area of 5,172.92 square kilometres (1,997.28 sq mi) with a population density of 1,460 inhabitants per square kilometre (3,800/sq mi). Aichi Prefecture borders Mie Prefecture to the west, Gifu Prefecture and Nagano Prefecture to the north, and Shizuoka Prefecture to the east. Nagoya is the capital and largest city of the prefecture.