From the Japan Post English site:
Suspension of Acceptance of International Postal Items to Canada
June 16, 2011
Japan Post Service is temporarily suspending acceptance of international postal items to Canada due to a postal strike. This suspension is effective from the date in the table below.
Starting date of suspension: June 17, 2011
For postal items already accepted and on the way to Canada, Japan Post Service will return them to the sender. The postage will be refunded to the sender, if desired.
Thank you for your understanding.