Suitcase or backpack for Japan

[Celeriacacaca]

We're off next month and I'm not sure whether we should take suitcases or backpacks. We are very economical packers and have done several holidays of 10 days travelling with a small hand luggage sized backpack each (stayed In Airbnb's with washing machines). We'll be doing the same this time but would probably take bigger packs, maybe 30l.

My indecision is that we'll probably do quite a bit of shopping while there especially when we're in Tokyo for the first week and will then be travelling on trains so will have more to carry. What do other more experienced travellers think is best?

I like to take a handluggage size small suitcase plus a small rucksack.

That way its easy and light enough on public transport, but you can wheel when walking. And then the smaller bag more useful for day to day out and about. I like having a small rucksack to fit water, cardigan etc when out all day.

We went to Japan last year as part of a longer holiday in SE Asia. To complicate matters, we were also on the way back to the UK after living abroad for a few years so we had a fair bit of luggage (two big cases plus smaller hand luggage bags). We were also travelling around by train and I was really worried about the luggage as the luggage compartments are really small on Japanese trains and on some trains I think there are restrictions on bag size.
I did some digging on line and discovered that most hotels,especially in Tokyo offer a luggage transfer service.
You pay a small fee and your bags are collected from the hotel and couriered to your next destination. It's really easy to do and worked brilliantly. Our big bags went from Tokyo to Takayama, onto Kyoto and finally Osaka Airport. We travelled light but were able to access the rest of our stuff at each stop. Can thoroughly recommend!