Japan's Emperor Akihito, who will abdicate at the end of April in the first such event in two centuries, marked the 30th anniversary of his enthronement on Sunday with a call for the country to open up and forge sincere ties with the world.
Princess Mako is one of only four royal grandchildren. The other three are her younger sister, Kako, her brother, Hisahito, and Crown Prince Naruhito's daughter, Aiko.
The Japanese government on Friday approved a one-off bill allowing ageing Emperor Akihito to step down from the Chrysanthemum Throne, in the first such abdication in two centuries.
The biggest crowds of his nearly three-decade reign thronged Japan's Imperial Palace on Friday to celebrate Emperor Akihito's 83rd birthday on what could be his last such appearance after expressing his desire to abdicate.