Itinerary advice

I am off to Japan for 14 nights in September, below is my draft itinerary, be grateful for any advice:

Day 1 - Arrive Tokyo

Days 2-4 explore Tokyo

Day 5- Hire car and drive to Nikko and explore the town and Lake Chuzenji. Stay night in Nikko

Day 6 - Drive to Nagano - on the way visit Yudanka for snow monkeys and maybe a couple of other stops on the way. It seems a lot of driving but am guessing the roads will be very scenic? Stay night in Nagano

Day 7 - Explore Nagano in morning then drive to Takayama. Stay night there.

Day 8 - Drive to Kamikochi, spend night in Matsumoto.

Day 9 -10 Drive back to Tokyo, drop off car then get train to Kyoto, spend two nights there

Day 11 - Train to Hiroshima - spend time there and visit Miyajima. Spend night in Hiroshina

Day 12-13 - travel to Osaka, spend 2 nights there, Aquarium looks a must here?

Day 14 - Train to Tokyo, last night there

Day 15 - travel to Airport

I guess my main worry is that the itinerary might be a bit rushed? Would like to see as much as Japan as I can in the 2 weeks though.

Combining Lake Chuzenji with the shrines of Nikko into a single day is possible but requires a fast travel pace. Note also that there is a risk of traffic delays in late September due to the popularity of autumn leaves, especially on weekends.

As for day 7, it makes little sense to go to Takayama for just overnighting there. I recommend to also allocate some times to see the city.

Also, since you pass Matsumoto on your way from Nagano to Takayama, I recommend to visit the places in the following order: Nagano - Matsumoto - Kamikochi - Takayama, and then travel to Kyoto directly from Takayama. It is considerably faster - and despite the rental car drop off fee, probably cheaper, as well.

Thanks for your advice. Do you think 1 night will be a bit rushed for Hiroshima? I was thinking of getting there around lunch time and visiting Miyajima in the afternoon. Then looking round Hiroshima in the evening and next morning, before getting a train to Osaka.

Miyajima and Hiroshima require at least half a day each.