[MMM]

Would the mountains and northern coast not be cooler in the winter, Nyororin?

I am not sure where the OP is located, but finding a relatively dangerous prefecture in Japan is like looking for an empty glass at a bounenkai. (Too obscure?) There just aren't any.

I have not traveled extensively in Chiba, but my impression was it is pretty urban. I lived in Amagasaki, which is an industrial city between Kobe and Osaka. Actually there are several cities between Kobe and Osaka but riding a train it would almost be impossible to tell where one city ends and the next one begins (a couple rivers give hints).

However, if you go north to central and northern coast Hyogo there is a real distinction between the forests and mountains and the very small towns the pop up here and there.