Former Japanese princess Mako sees her husband Kei Komuro, whom she finally married yesterday in a union that was put off by three years, as an "irreplaceable existence" in her life.

Mr Komuro, meanwhile, sees her as "a loved one with whom to spend the rest of my life", he said during the couple's first appearance as husband and wife.

The nuptials mean the eldest niece of Emperor Naruhito has shed her title to become Mrs Mako Komuro, in line with a Japanese law whereby princesses will lose their royal status when they marry a non-royal.

But Mr and Mrs Komuro, both 30, are optimistic as they look towards a future in which they are able to support each other through thick and thin.

"Marriage was a necessary choice for us, to continue living our lives while cherishing our feelings for each other," Mrs Komuro said, adding that she was relieved to finally be able to get married.

But she remains unwell and subject to panic attacks, she revealed.

She has been diagnosed with complex post-traumatic stress disorder over the slander and vitriol against the couple. Mr Komuro, whose father died when he was young, is shouldering a financial dispute between his mother and her former fiance over four million yen (S$47,000).

As a result, the marriage yesterday was a low-key administrative affair. To avoid the media glare, the couple did not personally register their marriage - an Imperial Household Agency (IHA) staff member submitted the papers on behalf of the couple.

All traditional marriage rituals were scrapped.

While the matrimony was generally well received, with congratulatory messages pouring in online and their union trending on Twitter, the newlyweds also drew online brickbats and accusations of "marriage fraud" and "naivety".

A poll by the Yomiuri newspaper this month showed more than half of the public in favour of the marriage, with 33 per cent against. Yesterday, at least one protest broke out, with demonstrators accusing Mr Komuro of "crimes".

"It was very painful and sad for me every time Kei was subject to criticism or unilateral speculation that he was ignoring my feelings," the former princess said yesterday.

"It was incredibly scary how even when unprovoked, false information can be taken up and spread as if it were true," she added.

Mrs Komuro's inner struggles came to the fore as she pointed to how some media outlets have reported falsehoods as fact.

This resulted in a last-minute decision by the IHA on Monday night to scrap the question-and-answer segment of the news conference, with seven pages of written responses to five pre-submitted questions given to the press.

"Some of these questions give the impression that the falsehoods are true," the couple wrote.

"We have been horrified, scared and saddened by the fact that false information has been taken as fact and that unfounded stories have spread."

In his opening remarks, Mr Komuro apologised to the public for the "inconvenience" that has arisen owing to the financial dispute. He added that it was his sincere wish to resolve the issue.

His mother, he said, has fallen ill from the stress to the point of having to quit her job, and has been advised by her doctor not to meet her former fiance to iron things out.

Mrs Komuro also noted that she had "limited opportunities to speak publicly until now", which she said could have caused misunderstandings.

She said that talks over the financial dispute have progressed based on her suggestions, while Mr Komuro had also gone ahead with his legal studies in New York's Fordham University in 2018 - at the height of the dispute - at her encouragement.

However, the couple slammed insinuations that Mr Komuro had received preferential treatment in his university admission, saying that there is "not a single shred of truth" in that.

"We are starting a new life together. There will be obstacles in different forms going forward but as a couple, we will overcome these obstacles with our combined strength," Mrs Komuro said.

Mako's parents, Crown Prince Akishino and Crown Princess Kiko, said in a statement that the couple's resolve to get married "has never wavered", even after their planned wedding on Nov 4, 2018, was scrapped.

Mrs Komuro's younger sister, Princess Kako, said she has been pained to see the slander that the couple have been facing, but is delighted that her sister was finally able to get married.

The couple first met in 2012, when they were college schoolmates at the International Christian University in Tokyo.

They kept their relationship under wraps by dating discreetly, until Mr Komuro first asked for Mako's hand in 2017.

But the negative headlines over the financial dispute have seemingly made a villain out of Mr Komuro despite what on paper are solid credentials of a man whose father died when he was young, and who had worked his way through school, overcoming the odds to become a promising lawyer.

Mr Komuro has been separated from his fiancee since he left Japan for New York in 2018, returning only last month to prepare for the wedding.

The former princess, who turned down a 152.5 million yen payout for females who leave the imperial family, yesterday moved out of the Akasaka Palace.

She now lives in a condominium in Tokyo's Shibuya ward with Mr Komuro in a temporary arrangement to settle paperwork associated with being a commoner. This includes setting up a family registry with Mr Komuro, a necessity for a passport application.

They will then relocate to New York, where Mr Komuro has found work at a law firm where he is expected to draw US$205,000 (S$276,000) in his first year.

The couple declined to answer questions about their future yesterday, saying that it was their "private matter".

But Mrs Komuro did say: "I hope that I can build a warm family in an environment where I can spend my time calmly."