6 days in Japan - seeking onsen experiences

Hello,

I have the amazing opportunity to visit Japan for a second time! I am traveling for work and am planning to head out a bit early to explore new spots in this wonderful country. I'll have approximately 6 days of personal time. I'm looking for advice on where to go. I've done a ton of research, and I'm feeling a bit overwhelmed. On my first trip to Japan, I was able to visit Tokyo, Akita, Hakone and Kyoto. One of my favorite things to do is soak in an onsen. I like having a private onsen in my room as well as the ability to visit public onsens. I'm looking for advice on where to go this year. I'd love a town that has shops, restaurants and onsen! I also like to hike and didn't get to see Mount Fuji last time because it was covered by clouds. I have to be in Tokyo for work. I know I don't have much time so I'm trying to figure out what makes the most sense. Thank you for any advice you're able to offer because I'm currently going in circles with my research.

Choose the Onsen resort you like best in Kawaguchiko, Fujinomiya or Mishima,

Some even have an onsen in your room with a view of Mt Fuji.

So could you please clarify: You search onsen near Tokyo? Right?

If yes, try
* South: Hakone (touristic!), Atami (not so beautiful) or Izu
* West: Bessho (quite a journey, but very beautiful)
* North: Nasushiobara (Tochigi) or some of the remote Nikko Onsen. With Shinkansen even Onsentowns in Fukushima are somehow close (e.g. Tsuchiyuonsen)
* East: You could make island hopping (e.g. Shikine-jima)

you can consider Kusatsu in the Gumma prefecture.

Just adding to the previous lists Izu peninsula and specifically Shuzenji.

With 6 days to play with, you could pick one of several regions and do a nice tour, combining onsens, ryokans, and whatever else you have an interest in

We just stayed in Kinosaki-Onsen in the north of Kansai so not sure how easy it is to get from Tokyo. The town was so nice, it had 6 public Onsen and most of the accommodations provide you with a pass to visit those Onsen for free.
Most people get in the spirit and wear yukata (usually provided by the accommodations) and wander around town. There are a couple of shops selling alcohol where you can sit and get a draft beer or do some sake tasting between Onsen visits.
No idea what your budget is - we stayed at Tsukimotoya (mid range I think) where we took half board options that included huge meals (one night kaiseki and the other shabu shabu). No private Onsen in room but there was a small basic one onsite. We also spent a night at Ginka across the river, amazing private bathtub overlooking the river. You could also book private Onsen (2 options) plus they had a larger public Onsen with both indoor and outdoor baths overlooking the river. Very special place. They provided free shuttle into town.