The Seibu Tamagawa Line is an 8.0 km (5.0 mi) railway line in the western suburbs of Tokyo operated by the private railway operator Seibu Railway. The line connects Musashi-Sakai Station on the Chūō Main Line with Koremasa Station along the Tama River. The line has only six stations and is not connected to any other part of the Seibu Railway system. The only connection to any other rail line is a rarely used maintenance connection to the JR East Chūō Main Line that is used to transfer trains requiring inspection or major repairs to Seibu's Musashigaoka Vehicle Inspection and Repair Shop.