Born in Tokyo, Masako was educated at Belmont High School in Massachusetts before attending Harvard College, earning a B.A., magna cum laude, in economics.

The birth fueled the ongoing Japanese imperial succession debate, which had resulted in some politicians holding a favorable view on rescinding agnatic primogeniture imposed by World War II allies on the constitution of Japan.

However, with the birth of a son to Naruhito's brother, Prince Fumihito, in 2006, no amendments were made and Aiko remains ineligible to inherit the throne, so she cannot succeed her father.

As crown princess and empress, Masako has accompanied her husband on official visits to foreign countries and at ceremonies within the imperial court.

[9] It was here that Masako learned to play piano and tennis, joined a handicrafts club, and became interested in animals, tending several after school and deciding to become a veterinarian.

[19] After graduation Masako moved back to Japan, where for six months (April to October 1986) she studied law at the University of Tokyo to prepare for the Japanese Ministry of Foreign Affairs's entrance examination.

Her assignments included dealing with the OECD's environmental affairs committee ... by all accounts she acquitted herself well—her command of spoken languages, so rare in Japan, was a huge advantage—and was popular with most of her workmates.

[4][34] However, Masako's name disappeared from the list of possible royal brides due to controversy about her maternal grandfather, Yutaka Egashira, who while working for the Industrial Bank of Japan was assigned to take over management of one of its creditors the Chisso Corporation to prevent it from financial collapse.

Masako refused to marry the prince because it would force her to give up her promising career in diplomacy and severely restrict her independence and freedoms.

Although many were surprised at the news, as it was believed that the prince and Masako had separated, the engagement was met with a surge of renewed media attention directed toward the Imperial family and their new princess.

A government-appointed panel of experts submitted a report on 25 October 2005, recommending that the Imperial Succession Law be amended to permit absolute primogeniture.

Koizumi did not announce a timing for the legislation to be introduced nor did he provide details about the content, but he did note that it would be in line with the conclusions of the 2005 Government Panel.

Plans to change the male-only law of Imperial succession were shelved after it was announced in February 2006 that Masako's brother-in-law and his wife, Prince and Princess Akishino, were expecting their third child.

[50][51][52] In October 2014, she was present at a banquet held in honour of King Willem-Alexander and Queen Máxima at the Tokyo Imperial Palace, which was her first appearance in such a ceremony in eleven years.

[53] In July 2015, Princess Masako traveled to Tonga with the Crown Prince in order to attend the Coronation of King Tupou VI.

The Emperor and Empress of Reiwa era were enthroned (Sokui Rei Seiden no Gi) at the Tokyo Imperial Palace on 22 October 2019.

Naruhito and Masako's first trip abroad as emperor and empress took place in September 2022, to the United Kingdom to attend the state funeral of Queen Elizabeth II.

[59] Masako and Naruhito embarked on a three-day state visit to the United Kingdom in late June 2024, at the invitation of King Charles III.

[63] Masako has periodically been out of the public eye, largely between 2004 and 2014,[64] reportedly due to emotional disorders speculated to be caused by the pressure to produce a male heir and adjusting to life in the Imperial Family.

[71][72] In December 2012, at the time of her 49th birthday, Masako issued a statement thanking the Japanese people for their support and saying that she was still receiving treatment for her illness.

[91] After the fall of the shogunate, the Owadas participated in a salmon-fishing cooperative,[92] the proceeds of which provided schooling for many local children, including Hisashi and his father Takeo.