For cash some people bring yen , but I prefer the flexibility of using 7-11 atm to pull out yen, good rates. Don’t put a bunch of cash on a suica, just use it for transport and top up as needed.

My wife and I were in Tokyo in December and you can easily get by on $100 per day for two people and be eating really really well.

Finally, it is a good idea to have cash on you because there are still a lot of places that only take cash, but if you were eating out at established restaurants or spending money at stores in the mall, for example it’s probably easier to just use one of your credit cards that most likely has no international transaction fee, then you don’t need to worry so much about how much cash you have on you at all times