If you plan to come to Japan in autumn, I’d definitely recommend you to visit the Fujigoko area in Yamanashi prefecture. Here’s the top 5 reasons:
1) The air is cleaner and Fuji is more visible than summer!
A lot of people visit the area in summer and are often disappointed that they can’t see Fuji. Even people living in the area like me, sometimes can’t see Fujisan for weeks. So the chance for you to see Fujisan in this season is quite slim.