On 30 December 2004, the Imperial Household Agency announced the engagementof Princess Nori to Yoshiki Kuroda, a 40-year-old urban designer with the Tokyo Metropolitan Government and a longtime friend of Prince Akishino.
Upon her marriage, which took place at the Imperial Hotel, Tokyoon 15 November 2005, Princess Nori left the Imperial Family, taking the surname of her husband, the first commoner of non-aristocratic background to marry an Imperial Princess.
These changes in her status are demanded by a 1947 law that requires female members of the Imperial Family to relinquish their birth position, official membership in the Imperial Family, and allowance upon their marriage unless she marries the Emperor or another member of the Imperial Family.
Her parents, the Emperor and Empress, were in attendance at the wedding, as were Crown Prince Naruhito, Crown Princess Masako and other members of the Imperial Family.
While she will no longer be entitled to an imperial allowance, she reportedly received a dowry of over one million dollars.
Since royals often have wanted to marry someone below their station, a device known as the Morganatic marriage came to be accepted in many royal circles. 
In the context of European royalty, a morganatic marriage is a marriage between people of unequal social rank, which prevents the passage of the husband's titles and privileges to the wife and any children born of the marriage.
 It is also known as a left-handed marriage because in the wedding ceremony the groom holds his bride's right hand with his left hand instead of his right.
Generally, this is a marriage between a male of high birth (such as from a royal or reigning house), and a woman of lesser status (such as from a non-royal or non-reigning house, or with a profession that is traditionally considered lower-status). 
 Neither the bride nor any children of the marriage has any claim on the groom's titles, rights, or entailed property. The children are considered legitimate on other counts and the prohibition of bigamyapplies. Morganatic marriage was also practised by the polygamous Mongols as to their non-principal wives.
It was also possible for a woman to marry a man of lower rank morganatically.
The practice of morganatic marriage was most common in the German-speaking parts of Europe, where equality of birth between the spouses was considered an important principle among the reigning houses and high nobility. The German name was Ehe zur linken Hand (marriage by the left hand) and the husband gave his left hand during the wedding ceremony instead of the right.
Perhaps the most famous example in modern times was the 1900 marriage of the heir to the throne of Austria-Hungary, Franz Ferdinand, and Bohemian aristocrat Countess Sophie Chotek von Chotkowa.
 The marriage was initially resisted by Emperor Franz Joseph I, but after pressure from family members and other European rulers, he eventually relented in 1899 (but did not attend the wedding himself).
The bride was made Princess (later Duchess) of Hohenberg, their children took their mother's name and rank, and were excluded from the imperial succession. The Sarajevo Assassination in 1914, during which the couple was killed, triggered the First World War.
Although the children, or issue, of morganatic marriages were ineligible ever to succeed to their families' respective thrones, some children of morganatic marriages did go on to achieve dynastic success elsewhere in Europe.
The 1851 marriage of Prince Alexander of Hesse and by Rhine and German-Polish noblewoman Countess Julia von Hauke (created Princess of Battenberg), provided a sovereign prince of Bulgaria, and queen-consorts for Spain and Sweden, as well as (through female descent) the consort of the current Queen of the United Kingdom.
The present Spanish Royal Family and members of the British Royal Family, including the current Prince of Wales trace descent from her.
Likewise, the marriage of Duke Alexander of Württemberg and Claudine Rhédey von Kis-Rhéde(created "Countess of Hohenstein") resulted in the House of Teck. That family's most famous member, Mary of Teck, married George V of the United Kingdom, and the present British Royal Family traces descent from her.
By the way, in case you can't remember, both Prince William and Crown Princess Victoria joined their RIGHT hand to the right hand of their Commoner affianced when they wed.
https://en.wikipedia.org/wiki/Morganatic_marriage