Joe Jones at MutantFrog Travelogue (don’t let the name fool you, it’s a fantastic blog about Japanese culture, politics and history) has an excellent overview of the law and demographics of divorce and child custody in Japan,  especially when foreigners are involved. Jones is a lawyer, with extensive international experience. The topic has come up because of a fairly prominent ongoing dispute between a Japanese woman and her dual-citizenship former husband over child custody, involving both US and Japanese law. You can find details in the links of Jones’ post.