The Nihonkai (日本海, "Sea of Japan") was a seasonal overnight train which was operated by the East Japan Railway Company (JR East). The train ran overnight between Osaka Station and Aomori Station using the Tōkaidō Main Line, Kosei Line, Hokuriku Main Line, Shinetsu Main Line, Uetsu Main Line, and Ōu Main Line. From the start of the March 17, 2012 timetable revision, regular operations of the Nihonkai were discontinued, with services operating during busy seasonal periods only. While JR East has not formally announced its discontinuation, no services have operated since January 2013.