She will lose her royal status and has declined a $1.3m payment for leaving the family.
Japan’s Princess Mako has married her college sweetheart Kei Komuro – thus losing her royal status.
Under Japanese law, female imperial family members forfeit their status upon marriage to a “commoner” although male members do not.
She also skipped the usual rites of a royal wedding and turned down a payment offered to royal females upon their departure from the family.
She is the first female member of the royal family to skip both.
Princess Mako left her Tokyo residence at around 10:00 local time on Tuesday (01:00) to register her marriage, bowing several times to her parents, Crown Prince Fumihito and Crown Princess Kiko. She also hugged her younger sister before she left, news outlet Kyodo reported.
The couple are expected to hold a news conference later on Tuesday where they will make a brief opening statement and give written answers to five selected questions that had been submitted in advance.
This is because the princess “feels a strong sense of anxiety” about having to answer questions verbally, said Japan’s Imperial Household Agency (IHA).
There has been excessive media coverage around the couple over the years, which has caused the princess to suffer from post-traumatic stress disorder, the IHA had earlier said.
Princess Mako’s relationship has been met with controversy in the country.
She was engaged to Mr Komuro in 2017 and the two were set to wed the following year. But the marriage was delayed following news of Mr Komuro’s mother’s financial problems – she had reportedly taken a loan from her ex-fiancé and not paid him back.
The palace denied the delay was linked to this, though Crown Prince Fumihito said it was important for the money issues to be dealt with before they got married.
They are expected to move to the US – where Mr Komuro works as a lawyer – after marriage.