Originally Posted by
yul36
I am looking for ideas for a day trip or an overnight where there is decent hiking and a few good onsens. Anything a couple of hours by bullet train would work.
"A couple of hours by bullet train" could put you as far north as Aomori or as far west as Okayama. You might want to do a bit of research on your own first. Might I suggest staying relatively close and visiting Hakone?