Marriage may be an institution, but it's permutations have run the gamut from polygamy, a practice that dates to ancient times but is still allowed in certain areas, to the recent legalization in some places of same-sex partnerships, with everything in between.
Postwar Japan has seen a shift from family-oriented marriages in which parents play matchmaker to individuals pursuing true romance. With democracy, women attained equal rights in marriage in terms of assets and custody.
These days, the concept of marriage is a source of great worry in Japan, as couples are tying the knot later in life. This, the graying population and falling birthrate are causing headaches for society.