Notes on Individual Rules under the Japan-Korea Social Security Agreement

In case that you work as an employed person on board a sea-going vessel flying the flag of either country, if you would otherwise be compulsorily covered by the pension system of both countries, you will be subject only to the system of the country in which you ordinarily reside.
The procedure to apply for your Certificate of Coverage under this rule is the same as it is for general employees.

If you need to continue to work as a detached worker (or a self-employed person) in the other country for more than 5 years because of unforeseen circumstances, you may be granted extension of the period of exemption for up to 3 years. In this case, you continue to remain subject only to the system in your original country where you are detached from. If your application for the extension is not granted, you will be covered only by the system of the country in which you work during the period exceeding the initial 5 years.