I am reposting my map of the best motorcycle roads in Japan as it seems not to show up inside the previous post when visitors search.
If you open the map on to a new tab/page then you can see the map legend and easy pan and zoom. (click the icon on top right corner of map)
As you can see there are good roads everywhere and you can’t go too wrong no matter where you choose. For me the best riding I have experienced is in Kyushu and Shikoku which have a high concentration of great roads as well grand scenery and less traffic, particularly in the south of each of these islands. I also find the Shimane and Tottori prefectures to be very good inland and the Nara and Mie prefectures good away from urban areas. Looking to the north Tohoku has great riding, especially in the Aomori region.
In between you will find many good roads on the map but there is also a higher population density. Not to say you cannot enjoy those great roads but the metropolises of Osaka and Tokyo and the cities between and either side combine to give this part of Japan a different feel. If flying into Tokyo you may not have the luxury to explore further afield but if not constrained to the middle of the country then consider the other regions instead.
I have so far made no mention of Hokkaido despite no doubt this is where you would have heard is the best. Hokkaido is nice but the southern regions have more good motorcycle roads. Summer in Japan is humid and rain, except Hokkaido, so that makes it popular. Japan is highly mountainous but Hokkaido is open plains dotted with farms and flat straight roads – unique and special for the Japanese but less so for overseas visitors.
I have written much more detail about how and when to ride Japan in my previous article that tries to cover everything you need to know to ride Japan.