The eldest granddaughter of Japan's Emperor Akihito will marry for love and give up her royal status.
Princess Mako, 25, announced her engagement at a press conference in Tokyo on Sunday, local time.
Her fiancé, 25-year-old law firm employee Kei Komuro, is a commoner and marrying him means the princess will become one too.
Female members of Japan's Imperial family are legally obliged to give up their royal status if they marry a commoner, under the 1947 Imperial Household law.
Princess Mako's departure from the ruling family was inevitable, as there are no male royals left in Japan.
"I was aware since my childhood that I'll leave a royal status once I marry," Princess Mako told reporters.
"While I worked to help the emperor and fulfil duties as a royal family member as much as I can, I've been cherishing my own life."
The couple addressed the media for the first time on Sunday (local time), after the Emperor officially approved the engagement in a morning ceremony.
The couple met in 2012 while both were studying at Tokyo's International Christian University, and Komuro proposed in December 2013.
The princess works as a museum researcher at the University of Tokyo, while Kumoro is studying business law and working in a law firm.
The engagement raises the issue of Japan's shrinking Imperial family. When Princess Mako marries the family will be reduced to just 18 members, including the Emperor.
Only men can inherit the title of emperor, and there is only one male heir in the princess's generation, Prince Hashito, who will have his eleventh birthday this week.
Japan's Imperial family is believed to be the longest continuous monarchy in the world, but these restrictive laws may put its existence in jeopardy.