if you are looking for something similar to the verbier, st anton, charmonix, la grave, val disere or somthing like that, you will be disappointed. japanese ski resorts are much smaller, and older i would say. however nagano isn't too bad of a place.
closer to hiroshima, i would recommend
hachikogen ハチ高原 in northern hyogo.
the skis you rent are furthermore, to say the least, not the latest model.
ps. i thought the four valleys were in switzerland.