関門海峡
, historically called , is the largest and most populous main island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separates the Sea of Japan, which lies to its north and west, from the North Pacific Ocean to the south and east. It is the 7th largest island in the world, and the 2nd most populous after the Indonesian island of Java.