Also keep in mind that early July is usually still the "rainy season" in most places. (this past summer it "officially" ended around July 15th in most places). Its not necessarily rain all day everyday, but it rains more often than usual then, and if not rainy, then it can often be overcast and mountains can be covered in clouds/fog. Mt. Fuji views wold be a gamble indeed.
Hokkaido though tends to be out of the rainy season, and as far as temperature, it is much more pleasant in Hokkaido during summer as well