Just after the Russo-Japanese War to the middle of the Pacific War, the Ministry of Railways (later known as Japan National Railways and today's JR group) was operating the Shimonoseki-Busan ferry between Shimonoseki City and then-Japanese territory Busan City (today's Busan Metropolitan City) in Korea (today's Republic of Korea).
日露戦争直後から太平洋戦争中にかけて、鉄道省（後の日本国有鉄道→現・JRグループ）は下関市と当時日本領であった朝鮮（現・大韓民国）の釜山広域市との間に関釜連絡船を運航していた。