The proof of Canadian citizenship for a Canadian born abroad is a Canadian citizenship certificate. A child born outside Canada to a Canadian parent and meeting certain requirements is a Canadian citizen. However the child will not possess a birth certificate issued by a Canadian governmental authority and for proof of Canadian citizenship, the child will need to obtain a Canadian citizenship certificate. An application must be submitted to obtain this certificate. Although applications are processed in Canada, you may submit the application to a Canadian diplomatic office abroad. In Japan, such applications can be submitted to the Canadian Embassy in Tokyo.
For details on how to apply, please read How to Apply for a Canadian Citizenship Certificate for a Child Born Outside Canada.
The Embassy will not accept applications that are incomplete, or which have been incorrectly completed. Incomplete or incorrect applications will be returned to the applicant and will only be processed once all documentation has been submitted and/or the application correctly submitted.