We were in Japan last year.
I think you'll find a wider range of things but I wouldn't count on saving any money - Japan is very, very expensive.
You'll be amazed by the amount and variety of camera stuff available - One store I went to in Kyoto had every possible model of Olympus camera and lens on sale, along with all the official accessories like eyecups and straps - they also had comprehensive ranges of all the manufacturers I could think of including a range of Leica.
The shop was like a 5 storey Dixons selling everything from shavers and washing machines to mobile phones.
This is their website
https://www.yodobashi.com/
BUT when I checked out the prices the savings were minimal working at a nominal exchange rate of £1=150Y, today it's £1=132Y
I couldn't see any significant saving, a potential hassle with tax and the joys of international warranty - not sure how that works for Nikon but it's restrictive for Olympus.
I've just done a price check on the Olympus OM-D E-M1ii with 12-40 lens (because it's one I know).
You'll save about £60 on a £1899 kit BUT then there's the tax to work out.
We bought some clothes "tax free" which is done at the point of sale in shops that are covered for it. They pushed this quite hard but it's not very user friendly.
They fix the receipt into your passport and stamp across the receipt and the page so you can't tamper with it. You're supposed to declare it on the way out but as there was no one at the airport desk we didn't bother. The irritation was we'd only save a few £££ and it was a pain to go through the process in the store, plus it makes a mess of a page in your passport which is expensive to replace if it's full of stamps from receipts! I've had enough grief of US immigration for smudged stamps without them being in a character set they can't read
I imagine if you did the same thing with an expensive purchase and got stopped at the UK airport you'd have to declare the gear and pay the VAT + duty.
What we'd bought was below the personal limits anyway, I've never seen anyone stopped at the airport but I assume it must happen and technically we should all declare things over the limits.
Something you may find interesting is the range of stuff available in regular stores.
There's a chain called
Loft which has a photography section.
They had big ranges of reconditioned vintage lenses, film cameras, polaroids etc.
They also had every possible kind of strap and mount and loads of FujiFilm Instax
https://www.loft.co.jp/
Vintage and Retro by
AMc UK, on Flickr
Instax display by
AMc UK, on Flickr
Vintage Film Cameras by
AMc UK, on Flickr
I don't remember seeing any dedicated camera shops in Akihabara but they do exist - this article might be of use.
https://japantravel.navitime.com/en/area/jp/guide/NTJtrv1166-en/