It will be designated the 500 series. Eight 3 car sets will be built by KHI. Features include full active suspension on all cars and permanent magnet synchronous motors. The three car sets will be designed to couple/uncouple en route with other three car sets to expand/shrink consists depending on passenger demand and service patterns. Introduction scheduled for spring 2017. This is the first order for rolling stock by Tobu awarded to KHI since 1946.
http://www.tobu.co.jp/file/pdf/4c10174fc83e8d1045e7adde5e16c37a/150422.pdf?date=20150421135208