"Katokusozoku" aims to achieve directly the continuation of the family as an institution. The patriarch, responsible for family continuation, has to decide in advance who is the man to succeed him in the event of his death. He usually selects a certain son as the candidate for his successor. When he has no offspring at all, the patriarch often adopts both a boy as his successor and a girl as the successor’s wife. In Mukoyōshi adoption, it does not matter whether or not the boy and the girl concerned have blood relationship with the patriarch or with his wife.