Two routes: Japan-first or Vietnam-first
The first thing I learned is that marrying a Vietnamese partner generally follows one of two routes: "Japan-first" or "Vietnam-first."
Japan-first
File the marriage registration in Japan first. If the Japanese partner lives in Japan, this route tends to be smoother, since it skips travel to Vietnam and a health checkup requirement.
Vietnam-first
Register the marriage in Vietnam first. This applies if the Vietnamese partner lives in Vietnam, and generally requires the Japanese partner to travel to Vietnam at least a few times for interviews and to collect documents.
Honestly, my first thought was "if it means visiting Vietnam a lot, that's not so bad" - but once I considered needing to take time off work for every trip, I understood why so many guides recommend "Japan-first if the Japanese partner lives in Japan."
First, you need a "certificate of eligibility to marry"
Both routes require a document called a "certificate of eligibility to marry." It certifies that you are single and legally free to marry, and can be obtained at the Japanese Embassy/Consulate in Vietnam, or at a Legal Affairs Bureau in Japan.
The general flow of the Japan-first route
If the Japanese partner lives in Japan, the Japan-first route generally looks like this. The details shift depending on whether the Vietnamese partner holds a mid/long-term status of residence in Japan or lives in Vietnam.
Obtain the certificate of eligibility to marry (at the Vietnamese Embassy/Consulate in Japan, or a Legal Affairs Bureau)
Submit the marriage registration at a Japanese municipal office (confirm required documents like the family register in advance)
Complete the marriage registration on the Vietnamese side as well (in some cases this can be done via the Vietnamese Embassy in Japan)
Once both countries' procedures are complete, move on to the spouse visa application
Rather than "traveling to Vietnam repeatedly first," starting the process in Japan seemed like the more realistic option, workload-wise.
After marriage: the spouse visa process
Once the marriage is registered in both countries, the next step is the spouse visa process for the Vietnamese partner to live in Japan. The type of application depends on where the partner currently lives.
If the partner lives in Vietnam
You apply for a "Certificate of Eligibility." Once issued, you submit it to the Japanese Embassy in Vietnam to apply for the visa. After the visa is granted and your partner arrives in Japan, a residence card is issued.
If the partner already lives in Japan
If they hold a status such as student or technical intern, it becomes a "change of status of residence" application instead, which can be completed entirely within Japan.
What changed with the 2024 legal reform
One thing that surprised me while researching this was that, under a Civil Code reform that took effect April 1, 2024, the 100-day remarriage waiting period (which previously applied only to women) was completely abolished. Previously, a woman couldn't remarry until 100 days had passed since her prior marriage ended, and a "certificate confirming she is not pregnant" was also required. Neither is needed anymore. For anyone considering remarriage, this is a quietly significant change.
What "authenticity of marriage" means in the visa review
A point that came up consistently across multiple expert explanations is the concept of "authenticity of marriage." In particular, if there's an age gap of 20+ years, or if either partner has multiple prior divorces, the spouse visa review reportedly scrutinizes more closely whether the marriage might be one of convenience.
Even when the procedure itself is straightforward, several sources emphasized the importance of preparing evidence of your relationship history (photos, message logs, call records, etc.) in parallel with the paperwork. It made me realize that the video calls and messages we've kept up during our own long-distance relationship might end up mattering in a moment like this down the line.