In total, Japan has 6,852 islands. However, this definition only includes islands that are 100 meters in circumference or larger; a less restrictive definition would lead to a much higher count, while a more restrictive one would lead to a lower count. Only 430 Japanese islands are inhabited.
Most people in Japan live on four islands: Hokkaido, Honshu, Shikoku and Kyushu. Of these, Honshu is the largest and most populous by a wide margin; it's also the seventh largest island in the world, with a total length of 810 miles. One of the smallest islands in Japan, Aogashima, had a population of only 205 people in 2009, including 25 students.