The announcement will be made by the chief of the agency at a press conference. The 25-year-old princess, the eldest child of Prince Akishino and Princess Kiko, and her fiance-to-be, also 25, are expected to hold a press conference later on that day.

The agency moved up the timing of the announcement by several months from the initially planned autumn or later, after a flurry of media reports on May 16 that preparations for the couple's engagement were in progress.

The date of July 8, a Saturday, was chosen partly in consideration of Komuro, who has a job, at a law firm.

A series of rituals will follow the announcement, including a betrothal ceremony known as "Nosai no Gi" and "Kokki no Gi," in which a messenger from Komuro will visit the residence of Prince Akishino's family to relay the date of the wedding ceremony for him and Princess Mako. (Jiji Press)