Not everyone approves of this princess' wedding. She's going ahead with it anyway - CNN

"There are so many doubts and misgivings about Kei Komuro and his mom, and people fear the image of the royal family will be sullied," said Kobuta.

Pressures of Imperial life

The years of speculation and slurs have taken their toll on Princess Mako.

Earlier this month, the palace disclosed that she suffers from complex post-traumatic stress disorder (PTSD).

The princess "feels pessimistic and finds it difficult to feel happy due to the persistent fear of her life being destroyed," Princess Mako's psychiatrist, Tsuyoshi Akiyama, director of NTT Medical Center Tokyo, told media at the Imperial Household Agency.

The princess isn't the first Japanese woman of the royal family to feel the pressure of Imperial life.

The transition was difficult for Masako, who long battled with an illness doctors described as an "adjustment disorder."

"Each case of a female member of the royal family struggling with mental illness has involved different circumstances," said Ken Ruoff, director of the Center for Japanese Studies at Portland State University and author of "Japan's Imperial House in the Postwar Era, 1945-2019."

"In the case of then Crown Princess Masako, it revolved almost entirely around her being blamed for not producing the requisite male heir," he added.

"Fast forward to the case of Princess Mako, and it revolves entirely around her marriage being subjected to a level of scrutiny that few marriages are subjected to, especially when you consider that she'll be exiting the royal house as soon as she is formally married."

Under Japanese law, members of the royal household must give up their titles and leave the palace if they marry a commoner.

As there are only 18 members of the Imperial family, Princess Mako isn't the first to leave.

The last royal to do so was her aunt, Sayako, the only daughter of Emperor Akihito, when she married town planner Yoshiki Kuroda in 2005.

As a woman, Princess Mako wasn't in line to the throne -- Japan's male-only succession law prevents that from happening.

Her role in royal life was to support her male relatives.

As a departing royal, Princess Mako was entitled to a one-off million-dollar payment, but in an effort to appease a disapproving public, she has decided to forgo it.

After the wedding, she'll move to New York City where Komuro works at a law firm.

But while Princess Mako's "dramatic" exit from the royal family is somewhat comparable to "Megxit" -- the term for the British couple's departure -- Ruoff, the historian, said the similarities end there.