Osaka (9D8N) with easy wheelchair access

Hi. I'm going to Japan in end of March to visit my brother who is studying in Beppu. We decided to meet up at Osaka. My grandmother is joining us and she has difficulties in walking long distance. Most of the time she will be in wheelchair. My parents will be around too.

My current plan is:
day 1: Osaka Castle, History Museum
day 2: Namba
day 3: Osaka Aquarium
day 4: Kyoto: Fushimi Inari Shrine and Tofukuji Temple
day 5: Kyoto: Kiyomizu Temple, Kodaijo, Gion, Nishiki Market
day 6: Himeji Temple

I'm still unsure where else to go. When I decided to go 9 days, actually I planned to go Fukuoka and Beppu as well. However, it seems very expensive for the train and accommodation. Also, 9 days seems too cramped for everything.

Do you have any suggestion for places that I can go to? Also, is any destination for my current plan inaccessible for wheelchair?

Thank you!

I'm in a wheelchair and as far as I know Himeji castle is not possible. The garden around it is as well difficult with a wheelchair.

I've been to Fushimi Inari it has many steps, but even the first few Toriis are very beautiful!

Thank you!