Renting a car as a resident of Japan

I'm a Canadian who has been living in Kyoto for about three years. I go home to Canada periodically to renew my license and visit family, and I have an international driving permit, but not a Japanese license. I've been told by several rental agencies that I can't rent a car because I haven't lived in Canada for at least three months. I can't figure out if this is a policy or an actual law. Anyways, have any foreigners who live in Japan been able to rent a car under similar circumstances? Any agencies that don't check your passport or something?

For residents of Japan, international driving licenses are only valid for one year. Afterwards, you have to live in Canada for at least 3 months again before you can drive in Japan again on an international driving license again. If you drive with an international driving license anyway, you will be driving without a valid license which is a serious violation of the traffic laws and can get you into deep troubles.

Fortunately, if you have a valid Canadian license, you can get a Japanese license relatively easily without any tests. The only challenge: you have to be able to prove that you have lived in Canada for at least three months after getting your Canadian license.