Japan's Princess Mako has given up her royal status to marry her 'commoner' boyfriend after a four-year engagement

• Princess Mako of Japan married her "commoner" college sweetheart on Tuesday.
• The non-traditional wedding follows a four-year-long engagement marred by controversy.

Japan's Princess Mako married her "commoner" college sweetheart, Kei Komuro, on Tuesday in a low-key event without a traditional ceremony or reception, according to The Japan Times.

The wedding, which followed a four-year-long engagement, comes weeks after the Imperial Royal Household announced the princess had suffered post-traumatic stress disorder from the public scrutiny surrounding her relationship, Japan's public broadcaster reported.

It's also not the first time the couple, who met at university in 2012, broke tradition. In September, it was announced Mako is rejecting the $1.3 million payout offered to female members of the family who lose royal status by marrying "commoners."

Speaking at a press conference in Tokyo after their marriage was officially registered on Tuesday, Mako said "arbitrary criticism" and "incorrect" reporting about her husband made her feel "great fear, stress, and sadness," Reuters reports.

"I feel very sorry for those whom we have caused trouble," she said. "For us, marriage is a necessary choice to live while cherishing our hearts."

Komuro added: "I want to spend the only life I have with the one I love."

The Japan Times reports that he left Japan in August 2018 to study at Fordham University's law school, and reunited with Mako in October after three years apart.

According to Japan Today, Mako's parents, Crown Prince Fumihito and Crown Princess Kiko, released a joint statement calling the marriage "unprecedented" for the Imperial Royal Household, and hoping the couple make a "happy family."

Komuro and Mako, both 30, are preparing to move to New York City where he works in a law firm once she receives her first ever passport, according to Reuters.

In response, protestors on the streets of Tokyo have been demonstrating against the marriage. According to the BBC, most of the slogans concerned Komuro's mother.

Public outcry against Komuro and his mother is nothing new and relates to a financial dispute that surfaced in Japanese media in 2017, months after the couple announced their engagement. According to the Times of London, the controversy stems from Komuro's mother's failure to repay 4.3 million yen, or around $35,000, to her ex-fiancé, some of which went to her son's schooling.

When the story broke in 2017, the Imperial Household Agency of Japan announced their engagement would be "frozen" and postponed in light of the financial dispute, the publication reported.

Her grandmother Empress Michiko called her "naive" for continuing the relationship, it added.

The dispute led to insinuations among the public that Komuro is a "gold digger," according to the New York Times. He issued a 24-page statement in 2021 where he said he would settle the payment, Reuters reported.

As a female member of Japan's imperial royal family, Mako's decision to wed a "commoner" means she will have to give up her title, according to Japan's 1947 Imperial House Law, The Japan Times previously reported.

Hideya Kawanishi, an associate professor of history at Nagoya University, told Reuters that while she would never have been expected to ascend to the Chrysanthemum Throne, her and Komuro's association with Hisahito, her younger brother who may become Emperor, is said to be particularly damaging.

Representatives for the Imperial Royal Household did not immediately respond to Insider's request for comment.