The series 681 was introduced in 1992 as JR West’s first limited express electric multiple unit, developed as a successor to series 485 trains that served limited expresses between the Kansai/Tokai region and the Hokuriku region. The prototype appeared as a 9-car through formation, while production sets were built as 6-car and 3-car sets so they could be separated and joined in service. Over time sets were reversed and reorganized; some remaining sets used as Thunderbird augment trains have been modified with the conductor’s compartment removed, some doors widened for barrier free access, and received refresh work and repainting to match the renewed series 683 color scheme.