Because the 'Taisha' express train, which ran from Nagoya to Izumo City via the Obama Line, was connected at Tsuruga to a train organized at Kanazawa, it was difficult in the sea-bathing season to increase the number of its train cars, and therefore 'Emerald' was introduced as a means to supplement its operation.
名古屋から小浜線を経由して出雲市まで運行されていた急行「大社」は、敦賀にて金沢編成と併結する関係上、海水浴シーズンの増結が難しくその補完として運転を開始した。