What is Honshu the principal island of?

Honshu is the principal island of Japan. It is the largest and most populous island in the country, and is home to the capital city, Tokyo. Honshu is located in the central region of Japan, and is bordered by the Sea of Japan to the west and the Pacific Ocean to the east. The island is mountainous, with the highest peak being Mount Fuji, which is also the highest mountain in Japan. Honshu is home to a variety of landscapes, including forests, mountains, and coastal areas. The island is also home to a number of historical and cultural sites, including temples, shrines, and castles.