Tour of Japan including Hiking and Onsen in Autumn 2019

I'm a 26 year old female from the Netherlands. I speak Dutch, English and conversational Japanese. I have two months of previous travel experience in Japan, mostly focused in the southern region in Japan (Kyushu) and I've hit the bigger cities (Kyoto, Osaka, Tokyo) during a two week travel.

I'm planning on a trip from September 23 to October 17, starting off with a midweek in Tokyo with a short sidetrip to Saitama.
I'm still working on my travel itinerary, but I'm planning on a stop in the Nagano prefecture for an onsen/hike combination with another stop at Kamikochi (near Takayama) for another onsen/hiking combination in the Japanese Alps. Along the route there will be a few bigger cities such as Toyama, Nagano and Kanazawa with a detour to Nagasaki to get a feel of Dutch/Japanese history and Gunkanjima as a side trip.

On the last leg is a visit to Okunoshima aka Rabbit Island. It's an island filled with fluffy rabbits and a dark history. There was a poison gas plant on the island and there are some interesting ruins and a museum to visit.

If you happen to be in Japan around that time and want to meet up for a leg of the journey, let me know.
I'd love to have someone else to share the beauty of Japan with!

I have no preference when it comes to gender or age.
A good grasp of the English language is preferred.