Japan 2nd Time Itinerary Recommendations

Hello,
I traveled to Japan for 3 weeks for the first time about a year and a half ago with my family, visiting Tokyo, Hakone, Takayama, Kanazawa, Kyoto, Osaka, Nara, Hiroshima, and Fukuoka. I'll be traveling again in November for another 3 weeks, this time alone, and I'd like some advice on this itinerary I quickly threw together. I tried to find a balance between repeating cities and exploring new places (larger and smaller), while also being good for solo travel. I'd like to visit a couple cities that have hardly any tourists this time around. My current plan looks something like this:

1. Tokyo (4 days)

2. Izu Peninsula/Ito (3 days)

3. Sendai (3 days)

4. Hiraizumi (2 days)

5. Nagano (3 days)

6. Kyoto (3 days)

7. Osaka (3 days)

8. Kobe (2 days)

9. Departure from Osaka

Looking for recommendations on durations (too long/short) or alternate cities that might be a better fit than the ones I have here (although I'd like to keep Tokyo, Kyoto and Osaka).

Thanks