Hunt for coupons. At the door of every place, look for the coupon book and the watch for the people handing out the coupons on the streets, take the free tissues and the coupon sheets! Just avoid the ones that are handing out sleazy material, unless you are looking for that sort of thing
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I collect the Yoshinoya and Sukiya coupons, I can eat 3 meals every day for less than 1500 yen, or about 17-18 CDN total. I have always been able to eat cheaper in Japan than in Calgary. I don't think I can get a big bowl of pork ramen anywhere in Calgary for $5.
Mcdonalds is cheap with coupons to if you want to stick to North American tastes, Freshness burger does coupons offerings, like free fries, drinks whatever.
For the hotels, it takes some digging, good deals can be had.
I've never had trouble using my Canadian phone in Japan on Wifi, or cell over there, guess it depends what phone you have.
Credit card tip: Hopefully this common knowledge but--->phone your card issuer before you go to tell them you are going, or it will get declined everywhere, with the language barrier it can be a total PITA. As usual most places are M/C and Visa. Not much American Express support.