In Japan, a couple does not become legally divorced simply by agreeing to separate. A divorce by mutual consent takes effect when the couple submits a divorce notification to their local municipal office and it is accepted. No court proceeding is required, and this is a normal form of divorce in Japan.
Once the notification is accepted, the family register records that the marriage has ended and that the couple has divorced. Even if they have lived apart for a long time and already told others that they are divorced, they remain legally married until the notification is accepted. Their legal status is determined by the official filing, not by how they are living.
A person who changed their family name when they married will generally return to their previous name after the divorce. Keeping the married name requires a separate notification.
A child does not automatically take the family name of the parent they will live with or move into that parent’s family register. The family register records the arrangement for parental authority after the divorce, but changing the child’s name or moving the child to another family register may require separate procedures. These matters may feel closely connected in everyday life, but the system treats them separately.
The family register records facts about legal family relationships, including whom a person married, when the marriage ended, and the arrangement for parental authority over a minor child. It does not record every agreement made between the former spouses. Property division, child support, and arrangements for contact with the child are handled separately.
If a new family register is created or the registered domicile is changed, the current certificate may not show every event from the past. Earlier registers, however, still preserve records of the marriage and divorce.
Divorce ends the marriage. It does not erase the fact that the marriage existed or that it ended. The family register is designed to preserve changes in legal family relationships, not to remove parts of the past.