Second trip seems to need something more

Hello,
I've been in Japan last year and did a pretty standard first trip (tokyo - kyoto - nara - kamakura - nikko - koyasan - hiroshima -miyajima). This year I will have the opportunity of spending 9-10 more days there and I had thought of something like:
1 Kumano Kodo
2 Kumano Kodo
3 Shirayama - (Kurashiki) reach Noashima (wanted to go the sea in Shirayama or near)
4 Naoshima
5 Naoshima and Osaka
6 Kanazawa
7 Kanazawa
8 Tokyo
9 Tokyo
10 Tokyo
I feel like this trip has three highlights (excluding Tokyo) and that I could add something more, for example reducing Naoshima, removing Osaka and spending only one day in Kanazawa, though I really wouldn't know what to add. I had thought of going further down to Hagi or even change everything and go to Kyushu. I wanted to see Kinosaki, but the train detour is long and maybe unjustified.
Please, feel free to share any possible suggestion, I'd appreciate it

The Kumano Kodo is beautiful but takes ages to get anywhere. Possibly adding a day there may be an option. Your also not that far from Ise which is quite different than the Kumono Kodo.

Check my name on the bottom of this post for my travel reports on the Komono Kodo a few years ago.

Working on a place between Osaka and Kanazawa, have you thought of Hikone? It has a great little castle and a nice town. Or between Kanazawa and Tokyo there is Takayama (very nice though some find it a bit meh) or Bessho Onsen (great little Onsen town near Ueda) or Karuizawa (which has a nice hike from the top of town to a lookout).

I almost thought of suggesting Matsumoto Castle on the way back to Tokyo but Hikone is also a nice castle. It's a relatively laid back town which is a bit different than the other locations mentioned.

Thank you for the input. Really.
Also looking at your trip in Kumano Kodo, I think it might be a good idea to add an additional day there, since it seems like the area is quite full and worth it. Moreover I fear that the hike in August might probe more difficult than expected, thus being more laid back could help. Do you feel like this is a reasonable concern?

We were thinking of moving from Osaka to Kanazawa via train, so no problem for example in stopping in Hikone.
On the other side we were thinking of moving from Kanazawa to Tokyo via night bus, so stops along that way might be more difficult. Though we could reconsider if the money spared (give or take 50€) wasn't worth the missed places.

Again, feel very free to add anything that comes to your mind. This feedback has been really helpful