The oldest member of the Japanese Royal family, Princess Takamatsu, has died of blood poisoning at a hospital in Tokyo.
Members of Japan's royal family have been paying their respects
She was 92 and had had frequently been in hospital since undergoing surgery in February.
Correspondents say that the princess, an aunt of Emperor Akihito, took a modern role within the Royal Family.
In 2002 she published an article in favour of reforming the dynastic rules of succession to let a female take the Japanese throne.
Also known as Kikuko, Princess Takamatsu was the granddaughter of the last of the shoguns, Japan's feudal rulers.
She was the widow of Prince Takamatsu, a younger brother of Akihito's father, the late Emperor Hirohito. The couple had no children.
The royal household had planned to announce the marriage of Princess Sayako, the youngest child of Emperor Akihito and Empress Michiko, on Saturday.
This has now been postponed.
Japanese media reported the engagement last month, but an official announcement was delayed out of consideration for victims of a series of earthquakes in northern Japan.
Princess Sayako is to marry Yoshiki Kuroda, 39, a childhood friend who works in the city planning bureau of the Tokyo metropolitan government.