Koiwai Station
Lines. Koiwai Station is served by the Tazawako Line, and is located 10.5 km from the terminus of the line at Morioka Station. Station layout. Koiwai Station has a two opposed side platforms, connected to the wooden station building by a footbridge. The station is staffed. History. Koiwai Station opened on June 25, 1921. The station was absorbed into the JR East network upon the privatization of the JNR on April 1, 1987. Passenger statistics. In fiscal 2015, the station was used by an average of 496 passengers daily (boarding passengers only).