December attractions for elderly

Grandparents visiting Japan for Christmas vacation this year (if possible of course).
They've already come to Japan before and visited Tokyo, Hiroshima, and Toyama.
They were supposed to visit this summer, but can't.
The original plan was Kyoto, maybe Fukuoka, maybe Nagasaki.
A lot of things close around New Years, so I'm wondering if it's worth still going there.
If not, what else could an elderly couple do for fun that month?

December is an awesome time to visit though it can be a bit of a drama with closures as you mentioned. I visited the Izu peninsula in May last year and thought it would be a place to go in November/December. There are lots of onsens around if they are in to that. Otherwise, I've enjoyed Kyoto and Nara around that time of year, and the alps (Takayama and Shirakawa). I didnt really like Kanazawa that time of year as it was very slushy and rainy, also it did have a lot of closures over the Christmas/new year period.

Some public attractions close across New Year, but there are still a lot of places that remain open. The trip I did 2019/2020 NY I needed to make a couple of small changes, but it didn't impact the week travelling very much.
Some temples/shrines are much busier than usual, but there are so many places worth visiting - some might call them "second-tier" places - that deliver great experiences.
Are you planning Christmas - everything open - or actually NY - busy travel period?

I was in Kyoto over New Year's at the start of this year, and the only trouble I had with closures was not being able to visit a museum that was holding an exhibition I would have liked to see (which I only found out about when I arrived in Kyoto!).

So many of Kyoto's main attractions are shrines and temples, which remain open over New Year's. However, they do become extremely crowded - I was in shoulder-to-shoulder foot traffic at Yasaka Shrine for about half an hour just to get through the park, and then waited in line for more than one hour to get my goshuincho filled out! Other places can be quieter, especially earlier in the day; I visited Nijo-jo about 10am on New Year's Day for a special opening, and it was very pleasant to walk through (plus I got a souvenir New Year's sake cup and free sake for being one of the first 1000 visitors that day!).

I think Christmas in Nagasaki sounds like a great idea, because the area shares a long and unique tradition of Catholicism.

Another area I can think of is the Sea of Japan side of Chugoku Region such as Tottori, Shimane and Yamaguchi Prefectures. The seafood from the Sea of Japan is great during winter. Oden of that region, which is different from the oden in Kanto, is also a treat especially if any of you enjoy drinking warm sake at a oden bar in winter.

Nagasaki is known for its imported culture from China and Portugal, while Kyoto is known for its 8th Century Imperial culture, but various places in Chugoku Region (as well as many parts of Kyushu) is where you can feel the gods and myths that tells the stories of how civilization in Japan originally began. I love the pottery there as well.

Tottori and Shimane have been known to suffer very little from Covid, and the density of population is relaxed. In particular, the governor of Tottori is known to have been doing a good job in controlling the crisis, and I'm sure the prefecture will keep it that way when they start re-welcoming tourists from abroad.

Hope it helps.

Christmas illuminations are great. Research in advance and try to hit some of the better displays. Some of them continue on after Christmas, but some don�ft. Besides lights, Christmas decorations in various places are quite fun. I always enjoyed strolling the main streets of Ginza and looking at the window displays around that time.

Hot springs are very enjoyable during the winter season. Go before the New Year�fs holidays actually start (at that point they will get crowded).

I have had some wonderful scenic train rides in the period around that time. You have to watch out for the heavy travel days (people going back to their hometowns, and then returning to the cities). But if you pick the right days the trains are not crowded. January 1 is actually a good day for train riding.

Eat fried oysters and other seasonal foods.

If they�fre still around after January 1, shopping can be fun. There are some good sales, for example at large shopping malls. This is not for everyone, of course. People who like this sort of thing tend to love it, and people who don�ft generally cannot fathom why others do... For me personally I don�ft like shopping much in my own country, but find it quite fun in Japan. Some malls are even open January 1 these days, offering something to do when many other places are closed.

Speaking of Christmas illuminations, the one in Kobe, commemorating the 1995 Great Hanshin Earthquake, is very famous. I don't know how they're going to deal with the crowd this year, but that's another day-trip location from Kyoto.

Nagasaki can be quite challenging for the elderly. It is quite steep in parts.

How long are they in Japan?

What type of things do they like to do?

How much do they like moving and how mobile are they?

Jon B makes a very good point. I dont think I've been anywhere steeper. Not much good for those of us with a fear of heights either, although the Garden Terrace Hotel there was spectacular.

I must admit I was on a tour bus when I visited Nagasaki (a long long long time ago). You may want to hire a taxi for a day if you're touring the city with those having problem walking.

There's still lots you can do in Nagasaki without walking up and down hills. It is easy to get to the ropeway station for Mt. Inasayama and once up there you don't need to walk too much. Dejima is completely flat. Other attractions can be reached by public transit or cab (or tour bus). I kind of like the idea of going in the Christmas season because of the Christian traditions of the city, especially for tourists who have Christian traditions in their own heritage.

Late December (and early January) are good times to get fine views of Mt. Fuji. You stand a reasonable chance of seeing it just from Tokyo. For a closer view, there are many options for day trips. The standard, heavily-touristed spots (Hakone and the Fuji Five Lakes areas) will probably be less crowded than they have been for many years. But I would also suggest some of the less-famous (to foreign tourists) local spots. Minobusan has a wonderful temple and great views of Mt. Fuji, although you will have to do your homework carefully and make use of cabs to get to and from the ropeway station. (There is a very long, uneven set of steps in the temple complex that will probably not be good for the seniors, but it is possible to enjoy the temple, ropeway views, and mountaintop complex without much walking.) The Miura peninsula has some good options for recreational outings from Tokyo. (Keikyu has a recreation ticket that I've used before for a splendid day trip.) Miho no Matsubara in Shizuoka is another good place. These places are all interesting excursion possibilities that give foreign tourists a chance to see "the real Japan," as long as they don't have unrealistic or fantasized notions of what that is.