Is it possible for a couple of foreigners to divorce in Japan? What if one of them returns to their home country and there is no communication?

Even couples of foreigners can divorce in Japan.

If you have an agreement on divorce, you can have a consultation divorce if your home country allows for a consultation divorce, but if you do not have an agreement, you can use a mediation divorce or a trial divorce. Even if there is an agreement, if the home country does not allow a consultation divorce, we will use a mediation divorce or a trial divorce.

Also, if one of the couples returns to their home country and the whereabouts are unknown, a divorce proceeding can be filed in a Japanese court.