I always saw Japan as a national version of Marks & Spencers (a major department store in the UK where they refused to take credit cards until the late 1990s). Things have changed in the past few years and as I work for Visa, I'm seeing that contactless and mobile payment seems to be overtaking credit cards in Japan, especially in Tokyo. But you still have to be careful not to be caught without any cold hard cash.
I never had any issues with carrying £200 worth of cash in my wallet. It did make me feel really rich when I was getting the wonga out, haha.
I did take travellers cheques but the hassle was so phenominally retarded that I gave up and just relied on my student loan that had just come in (£2000 interest free, thank you very much!) and withdrew from that. Basically at one point, I had to resign one travellers cheque about twelve times because the signatures did not match
perfectly which was immensely embarrasing.
So:
- If you want to use credit, keep some cash on you just in case.
- Just carry cash and use Post Office and Citibank ATMs
- Travellers Cheques may be more hassle than they're worth.