How many volcanoes are there in Japan? There are around 200 volcanoes, 60 of which are active. How far away is Japan from mainland Asia? Located on the western tip of Kyushu island, Nagasaki is the closest prefecture to mainland Asia. The island of Tsushima, part of Nagasaki Prefecture, is only 53 kilometers (33 miles) from the South Korean seaport Pusan. How big is Japan? Check out our Nature and Climate section. What is the highest mountain in Japan? How tall is it?