data seto japanSeto, city, Aichi ken (prefecture), central Honshu, Japan, northeast of Nagoya. Seto, established about 1230, is known for its porcelain (Seto ware). Since the Meiji period (1868–1912),Seto, city, Aichi ken (prefecture), central Honshu, Japan, northeast of Nagoya. Seto, established about 1230, is known for its porcelain (Seto ware). Since the Meiji period (1868–1912),