ideas for minimal walking?

Hello,
I am running the Tokyo Marathon on 3/5. We have planned the itinerary for the rest of our trip days, but are looking for suggestions for the day before, Saturday 3/4, which has minimal walking so I can stay off my feet and rest my legs. Normally in other cities I have raced, we have done something like a hop on/hop off bus tour so I could mostly sit and we could still see things. However, the only one I found in Tokyo doesn't have any tours in Feb/March, I'm guessing they don't run in the colder months? I don't want to waste the whole day, but I need to find something with less walking than our other day plans.

1) a day spent in an onsen lying lazily in the warm water.
You could make a full daytrip out it or just visit one in Tokyo. My favorite in town is Sakura onsen.
2) a river cruise in Tokyo. Still will involve some walking

good thinking re onsen. If you went to Bessho Onsen there would possibly still be sakura in bloom as it flowers later there.

@Lazy Pious, that is March 4th and March 5th, I think OP is American and we write dates month first and then day.

lol, you crazy yanks....I nearly lost my business website a few years back over the same thing - I thought the domain renewal was 1 June instead of 6 Jan, and ignored the reminders over the Christmas break...

OK, scratch that suggestion

Skybus seems to be in operation.
It seems to be equipped with a voice guidance system by GPS in English, Chinese and Korean.
https://www.skybus.jp/course/?id=1633770801-442553
https://www.skybus.jp/course/?id=1499778615-966121
The Tokyo Marathon Expo will also be held on March 4th.
https://www.marathon.tokyo/en/events/expo/

Possibly get a JR day pass (tokunai pass) and plan an itinerary based on places that are very close to JR stations. (I have heard of people who took the Yamanote line all around its full circuit�c I have never been tempted to do such a thing myself, but as long as you avoid rush hour, it might be interesting in a way. Of course, you could get off and on as many times as you wanted, with a day pass.) The thing about JR trains as opposed to the subways is that you are above ground the whole time, so you can see things. Besides the Yamanote line there are other JR lines you can use with the Tokunai pass. Among other things, there is an aquarium (Tokyo Sea Life park) that is a fairly short walk from a JR Station (Kasairinkaikoen). It is not the best aquarium in Japan, but is inexpensive and unassuming (I rather like it myself). But there are loads of other places near JR Stations. So you could easily plan your own HOHO day. Because steps are considerably more stressful on your knees and feet than just walking on the flat, you might want to force yourself to use elevators or escalators even though the platforms are not so high and it�fs tempting just to use the stairs.
https://www.jreast.co.jp/multi/en/pass/tokunai_pass.html

Ah, I just realized that on the day in question, there won�ft be a rush hour, since it�fs a Saturday! All the better for riding trains around the city.

Another above-ground train option, if JR is too prosaic for you, might be the Toei (Toden) Arakawa streetcar line. There are fewer options for �ghopping,�h but the ride itself might be more interesting in a sense. I have done parts of it although not for the scenery. You can get a day pass for it, too.

https://www.kotsu.metro.tokyo.jp/eng/services/streetcar.html
https://en.wikipedia.org/wiki/Toden_Arakawa_Line

March 4th is too early for Cherry Blossoms, but it is on the tail end of Plum Blossom season. Try going to one of the places that will be having a plum blossom festival in Tokyo.

I hope this link to a page in Japan Guide works: https://www.japan-guide.com/e/e2013.html

Good Luck in planning your trip.

Thank you everyone for your responses!
Yes, I�fm American and meant March, not May. I appreciate everyone�fs answers.