Where to exchange CAD to JPY?

I'm going on a trip to Japan in January and I've researched a bunch about exchanging and purchasing JPY but I've gotten contradictory advice. Some say it's better to withdraw cash from Seven Bank ATMs at either the airport or a 7/11, and some say it's better just to exchange at your home banks. I also know that Seven Bank ATMs don't take Interac Debit cards, which is what I have, but I don't know if I would want to use my credit card at the ATM. I would like some advice on exchanging CAD to JPY. Thanks all.

When you use your card in a Japanese ATM, the exchange rate is determined by the issuer of the card. Some cards offer a good rate, some don't.

The exchange rates offered at currency exchange offices in Japanese airports are usually considered good. I don't know about those in Canada

I also know that Seven Bank ATMs don't take Interac Debit cards

I don't know where you got that advice from but I can tell you as a fellow traveller from Canada whose been to Japan several times, it's wrong.

Both 7-11 and Japan Post Bank take Canadian debit cards.

Though, I will point out one exception I ran across during my last trip in 2015. I bank with TD-CanadaTrust and on my trips in 2008, 2011, and 2014 I had no problems at 7-11 ATMs with my TD debit card. Before I went on my 2015 trip TD issued me a new debit card that was a Visa debit card (my previous card was not a Visa debit card). This card did not work in the 7-11 ATMs but worked fine in the Japan Post Bank ATMs which you can find all over Japan.

I have not heard of anyone else having problems with any of the other big bank (RBC, Scotia, BMO, etc) debit cards at 7-11 ATMs. I've just found several complaints online about the TD Visa Debit card not working.

However, if you don't care to risk it and want to carry and exchange cash, I suggest exchanging some in Canada first so you have some Yen with you. After that you'll have to find a currency exchange place....I do not recommend doing it at a bank in Japan it's a long and convoluted process. I know there are a couple of currency exchange places in Tokyo station, see map here: http://www.tokyostationcity.com/en/information/

Googling "Tokyo currency exchange" brought up several other locations.

Canadian Dollars are not considered to be an attractive currency in Japan and therefore the exchange rate at the exchanges is quite bad. If there is a way to buy Yen in Canada, I would recommend that option over bringing your paper currency to Japan. I haven't looked at the exchange rates for CAD in quite some time, but when I used to glance at the rates at Narita, I was surprised to see how bad it was for CAD. I don't think that has changed in the recent years. It's just not an attractive currency. This information is for paper currency you'll be bringing into the country. I don't know about what the ATMs would charge, since there's no need to "manually handle" Canadian Dollars in that case.

Thanks very much for your advice, pals.

Regarding the Canadian debit card thing, I saw from a few people that the ATMs don't take Interac Debit but I guess that's false. I'll be exchanging some yen in Canada and then if I need to, I'll take out some at the ATMs in Japan.

I have been to Japan several times and was just there this past April. I brought with me my CIBC debit/VISA card and Tangerine(Cirrus/MasterCard) card.
I used my Tangerine card to withdraw money from my chequing account at Seven Bank ATM inside 7 Eleven. 7 Eleven are more readily accessible than Japan Post ATMs. I had no issues withdrawing Japanese Yen and was charged a foreign ATM fee of $2 Canadian plus a foreign exchange fee of about +2.5%.
However, I had to notify Tangerine about a travel notification or your account might get locked out.
Prudent advice from previous poster about exchanging some Canadian dollars to Japanese Yen to get you started. I would get my money exchanged at Narita airport currency exchange as they tend to give you the better rates than money exchanges elsewhere. This is just based upon my own observations.