> [T]he koseki ... is an integral part of Japanese family law that doesn’t actually care about families beyond ensuring that the legally significant aspects of them are identifiable to the Rest of the World. Thus, a koseki extract today will show a marriage, but not whether the spouses are living together. The system also doesn’t care (i.e., show) if the registered father is not the biological father. It doesn’t care whom the kids live with after a divorce or if a divorced parent is paying maintenance or how often (or if) he sees his children.