Japan remains one of the few countries where its royal family operates under agnatic primogeniture rules, meaning that women are entirely banned from inheriting the throne.
While there had been previous discussions about changing this following the birth of Princess Aiko, these were put to rest when Crown Prince Fumihito welcomed a son, Prince Hisahito.
However, due to the shrinking size of the Imperial Family, this week, Japan's parliament passed a bill that will impact succession laws. Although women still won't be allowed to accede to the throne, royals will be allowed to adopt distant male relatives over the age of 15 to allow them into the line of succession.
These possible male heirs hail from 11 former branches of the family which were removed following World War II; however, they will not take the place of anyone who is already in the line of succession.
At the moment, there are only three heirs to the throne behind the current Emperor, those being his brother, Fumihito, nephew Hisahito, and 90-year-old uncle, Prince Hitachi.
The new rules have come into effect because if Hisahito doesn't produce a male heir, then the family line would become extinct.
© Associated Press / Alamy Stock PhotoHowever, despite still being barred from the throne, there is a positive move for Princess Aiko and future female members of the family. Previously, upon their marriage to a commoner, female royals would have to renounce their place in the Imperial House, including their royal titles, but this has now been axed.
Although this will allow for more working royals, if they produce male heirs, they will also be barred from the line of succession.
© Yuichi YamazakiAiko, 24, the only child of Emperor Naruhito and Empress Masako has not yet taken a partner, so currently retains her title as Princess Toshi. She has been stepping into the limelight in recent years, including her first solo outing in 2024, and her first solo overseas engagement the year after.
Princess Mako's marriage
The most recent example of a Japanese royal losing her title was Princess Mako, following her marriage to her university sweetheart, Kei Komuro. The couple married in 2021, and shortly after the ceremony, they moved to New York City.
Ahead of her move, Mako said: "What I would like is to just lead a peaceful life in my new environment. We are starting a new life together. There will be obstacles in different forms going forward, but as a couple we will overcome these obstacles with our combined strength… I hope that I can build a warm family in an environment where I can spend my time calmly."
The couple have made several changes since their move nearly five years ago, namely the arrival of their first child. The arrival was confirmed on 30 May 2025, although the initial post didn't confirm the baby's gender or the arrival date.
A statement said that "as well as their other children, are delighted about the birth and are wishing for the happiness of the Komuro family".
