Best onsen and kaiseki

Can anyone recommend a beautiful Onsen and Ryokan that serves the best Kaiseki close to Tokyo or Osaka. Thanks

Izu peninsula comes to mind. From your request I guess that money isn�ft tight. I stayed at this ryokan several years ago and it was magnificent:

https://www.ochiairo.co.jp/facility/

I have had two Kaiseki near Osaka, the more memorable one was unexpected. Both were not at a Ryokan.

I did a temple visit to Koyasan. I stayed at a temple, and not a Ryokan. The evening meal was a Kaiseki.

I also went to Shirahama, which is a Seaside Hot Springs Resort town. Once again, I was not at a Ryokan, but a resort hotel by the shore.

I was expecting a buffet meal, but the hotel was hosting a class trip, so the main dining area was being used by 100-200 students. The other guests were given times to their upscale restaurant, and the Kaiseki was fantastic.

I have stayed at several Ryokan, and the only ones that came close to that meal was a Ryokan across from Yakushima Airport, and a Ryokan near the cave in Takachiho. In general, I have figured out that I do not sleep well on a futon, and prefer a bed.

Some of my best meals in Japan were ones where I just wandered into, like on a side street in Kyoto, which I have no idea if I could find again.