The Kaikyō Line is an 87.8 km (54.6 mi) railway line operated mainly by the Hokkaido Railway Company. The line connected Naka-Oguni Station in Sotogahama, Aomori, through the Seikan Tunnel between Honshu and Hokkaido, to Kikonai Station in Kikonai, Hokkaido. Two stations on the Tsugaru-Kaikyō Line, Tappi-Kaitei Station and Yoshioka-Kaitei Station, were inside the tunnel.