The is an AC electric multiple unit (EMU) operated by Hokkaido Railway Company (JR Hokkaido) on Sapporo area suburban services in Hokkaido, Japan since 1988. Design The trains were built jointly by Hitachi, JR Hokkaido (Naebo Factory), Kawasaki Heavy Industries, and Tokyu Car (Yokohama). Fleet As of 1 April 2012, the fleet consists of 135 vehicles, formed as 23 3-car sets and 11 6-car sets. Variants 721-0 series 721-1000 series 721-2000 series 721-3000 series 721-4000 series 721-5000 series References Electric multiple units of Japan Hokkaido Railway Company Train-related introductions in 1988 Hitachi multiple units Kawasaki multiple units Tokyu Car multiple units 20 kV AC multiple units