Following her betrothal at age fourteen, Nagako was withdrawn from this school and began a six-year training program aimed at developing the accomplishments deemed necessary for an empress.

[2] Nagako was betrothed to her distant cousin the Crown Prince Hirohito, later the Emperor Shōwa (1901–1989) at a very young age, in a match arranged by their parents, which was usual in Japanese society at that time.

In 1917, at the age of 14, she and other eligible candidates for betrothal participated in a tea ceremony at the Imperial Palace while the Crown Prince watched unseen from behind a screen.

[4][7] Their marriage marked the last time a future empress was chosen from minor princely families that usually provided brides for the main line.

[8] It was only on 23 December 1933, almost ten years after their wedding, that the young couple had a son, and gave Japan an heir, in the birth of Akihito (明仁).

She initially came to live in the palace during the time when people there spoke an archaic imperial form of Japanese that has largely disappeared.

[4] Her role required her to attend special ceremonies such as those for the 2600th anniversary of the legendary foundation of the Empire of Japan in 1940 or the conquest of Singapore in 1942.

[2] Their children were sent to the countryside,[8] while she and Hirohito resided at the Obunko imperial air-raid shelter, which was built in the Fukiage Gardens on palace grounds.

[4] NHK reported that "her heart was in pain when she saw the emperor deeply agitated every day during and immediately after World War II.

"[8] After the occupation of Japan, the court became more accepting of Western and foreign traditions and Nagako took English lessons from two American tutors.

[8] It is not clear whether Nagako openly disapproved of her son Akihito's choice of a wife when he decided to marry commoner Michiko Shōda, but it was widely reported in the press that she and her daughter-in-law had a strained relationship.

[11] A talented artist, two collections of Nagako's paintings, which she signed as Toen or Peach Garden, were published and she gifted the UK's Queen Elizabeth II with one of her pieces in 1971.

[7] On 15 June, the IHA director-general told certain segments of the press that her condition had taken a turn and it was reported that she had slipped into a coma on the next day after her blood pressure dropped.

[4] Her son Akihito, who had been carrying out public engagements earlier in the day, immediately went to Fukiage Palace and reportedly held his mother's hand as she died.

[14] Emperor Akihito granted his mother the posthumous title of Empress Kōjun (which means "fragrant purity"), drawing inspiration from the Kaifūsō.

[1][7] Her final resting place is in a mausoleum named Musashino no Higashi no Misasagi, near that of her husband within the Musashi Imperial Graveyard.