If you are a spouse of a Japanese citizen and planning to move to Japan to live, please make sure to obtain your certificate of eligibility before you move to Japan.
You are allowed to live in Japan with your spouse and wait for the certificate of eligibility to be issued as a short-term visitor, but you must leave Japan and be separated from your spouse for a while if the certificate of eligibility is not issued before the end of your period of stay.
If a Certificate of Eligibility is issued after arriving in Japan, it is possible to change the status of residence in some cases within Japan. However, considering the risk of the short-term stay visa expiring, it is much better to obtain the Certificate of Eligibility before coming to Japan.