Legal marriage age for girls in Japan is 16, if all parties including the parents agree to it. Age of consent varies more, and generally not accepted below 18.
This used to be the case but it's no longer like that. I did some AI-assisted searching (checking a couple of links provided as sources, of course).
From what I've found in April 2022 the Japanese Civil Code changed the minimum age of marriage for both men and women to 18, abolishing the 16 minimum for women with parental consent provision. Since the age of majority was lowered from 20 to 18 at the same time an 18 or 19 year old would no longer require parental consent like they did before.
There also used to be a provision that a woman could not remarry for 100 days after a divorce (for paternity reasons) but that was also abolished.
(I must note that even though "adulthood"/majority is now 18 like in the US you still can't legally consume alcohol until and older age. Old enough to vote, borrow money, get married, and die for your country, but not old enough to drink.)
| Feature | Old Law (Pre-April 2022) | Current Law (2026) |
| Min. Marriage Age (Men) | 18 | 18 |
| Min. Marriage Age (Women) | 16 | 18 |
| Parental Consent Needed? | Yes (if under 20) | No (at age 18+) |
| Legal Adulthood Age | 20 | 18 |
