Honshu , historically called Akitsushima , is the largest and most populous 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 seventh-largest island in the world, and the second-most populous after the Indonesian island of Java.

The Japanese archipelago is an archipelago of 14,125 islands that form the country of Japan. It extends over 3,000 km (1,900 mi) from the Sea of Okhotsk in the northeast to the East China and Philippine seas in the southwest along the Pacific coast of the Eurasian continent, and consists of three island arcs from north to south: the Northeastern Japan Arc, the Southwestern Japan Arc, and the Ryukyu Island Arc. The Daitō Islands, the Izu–Bonin–Mariana Arc, the Kuril Islands, and the Nanpō Islands neighbor the archipelago.