The Sunrise Seto (サンライズ瀬戸, Sanraizu Seto) is an overnight sleeping car train service in Japan operated by the East Japan Railway Company (JR East), Central Japan Railway Company (JR Central), West Japan Railway Company (JR West), and Shikoku Railway Company (JR Shikoku) since July 1998.
The Tōkaidō Main Line (Japanese: 東海道本線, romanized: Tōkaidō-honsen) is one of the most important railway corridors in Japan, connecting the major cities of Tokyo and Kobe via Shizuoka, Nagoya, Kyoto and Osaka. The line, with termini at Tokyo and Kobe stations, is 589.5 km (366.3 mi) long, not counting its many freight feeder lines around the major cities. The high-speed Tōkaidō Shinkansen largely parallels the line.
The term "Tōkaidō Main Line" is largely a holdover from pre-Shinkansen days; now various portions of the line have different names which are officially used by JR East, JR Central, and JR West. Today, the only daily passenger train that travels the entire length of the line is the combined Sunrise Izumo/Sunrise Seto service which runs overnight. During the day, longer intercity trips using the line require several transfers along the way.