data seto japanThe Setouchi Triennale is one of the country's foremost contemporary art festivals, held every three years on the islands of the Seto Inland Sea. The 100-day festival, whichSeto (, Seto-shi) 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 km . The total area was 111.40 square kilometres (43.01 sq mi).