how and where do i convert 30,000 dollars worth of Canadian cash into Japanese cash?

Question

at an air port? a bank? assume i have 30,000 dollars in CASH, and i want them turnedinto JAP cash.

Answer 1

For such a large amount, you would definitely want to go to a commercial bank. A regular currency exchange will cost you quite a bit in commission, and a bank (especially a Japanese bank like Sanwa Bank) should give you a better exchange rate. For such a large amount, you will need to give the bank advance notice, since they won't have cash on hand.
I hope you aren't in the USA. All transactions of $10000 or more must be reported to the IRS, no matter if it's a bank or a currency exchange.
Here is another thought. For that much, you should call around to see who has the best rate. You may find that the rates in Canada and the USA are poor enough that you might actually come out ahead buying a plane ticket to Tokyo and exchanging the money there. A ticket from LAX to Tokyo NRT can be had for around $600 or around 2%.
Forget the airport or regular currency exchange. It will cost you about 5% on the lousy exchange rate.

Answer 2

Zoxx is right. Really review your chances of going there to exchange the $$. You can have it wired home and the exchange rate is going to be much better because you only have to deal with one exchange, rather than two if you do it in North America.
Also, contact the Japanese embassy for information on exchange rates at various outlets in NA. Hopefully, you'll find them helpful.
Lastly, and I include this only because of the high dollar amount you are talking about....
Consider a double exchange. Sometimes it will help to exchange to a third currency, then exchange that third currency into the currency you really want. Sounds silly, but all depending upon the rates and who does it for you, a difference of one or two hundredth of a point in the rate can add up.