Japanese currency, not US Dollars, is expected for visitor services. Talking louder
and slower in English is also stupid. Go ahead, use dollars, but bankers would
be more honest about the exchange rate.
The other big expense you'd have would be food..you could cheapskate your way through for about 1000 yen or about US$ 9 a day, but that's really roughing it.
The other expense would be admissions fees, any souvenirs... There are some places that are very cheap or free.
WHERE in Japan you plan to be. Prices are not the same all over Japan.
Your minimum standard for a meal and what else you plan to do such as buying souvenir visiting parks, museums, etc. If you plan to live of cup of ramen noodles, drink water, and buy no souvenirs or visiting any sights that require an entry fee, you could do it for maybe $6. It won't be very filling and you are not going to enjoy it, but you could do it.
Depends on what you desire to eat, places you want to visit (entrance fee) and any shopping you want. Shall I guess if you want diamond jewellery, or some cheap paper fans.
$200-300 per day should give you enough for some nice meals and stuff to do.
Can it be cheaper ? YES Can it more expensive also YES.
A bowl of noodle soup is a cheap meal.Refilling your bottle of water before you venture out is cheaper than buying it during the day.
Making your own meal is cheaper than buying one ready made.