They’re men born as women, and yes, you can call them 'onabe'

DNA doesn't lie.

It's these women's business how they lead their lives I suppose, but we are what God made us. Someone born male cannot become female and vice versa.

What does that involve for women?

I read the full article, it seams that gender reassignment surgery is not required for the change of status, it said they are still physically female. According to the article*

And if one decides to take the step of physically undergoing a sex change or legally becoming a man, the process is complicated and drastic. As stipulated in the Seidoitsuseishogaisha no Seibetsu no Toriatsukai no Tokurei ni Kansuru Horitsu (“Act on Special Provisions for Handling Gender for People with Gender Identity Disorder”), to legally change one’s gender, both transgender men and women must be physically unable to have children, which means transgender men must undergo a hysterectomy and oophorectomy. As can be seen by the title of the above law, being transgender is officially classified as a shogai (disorder), and one must be diagnosed with the disorder to undergo treatment, which in this case is surgery to prevent a transgender person from bearing their own children.

First visited one of these places almost 25 years ago. Seems the whole culture is unchanged. In general, I like the way bars of this kind are welcoming to everyone. They lack the hostility one sometimes encounters in Western bars of similar types.

Do they also change their chromosomes from XY to XX?

With Japan having so many 'straight' men that use more 'product' than many women do, I find it hard to tell the difference and frankly couldn't care less. Let people live their lives as they want to. Happy people usually don't make trouble for society. The ones who suffer, some quietly and some of those who end up snapping do which eventually costs us all in many ways. Live and let live.

What does that involve for women?

Guess.

or look it up. "reassignment surgery". Wikipedia will have plenty of safe-for-work information.

What does that involve for women?

Guess.

More like a gender/sexual identity counselling clinic than a bar - at least as it comes across in the article.

Good marketing ploy, but in the end I suppose everyone ends up with a drink anyway and that is good.

"What does that involve for women?"

Writing very difficult kanji on very difficult forms...

He has also undergone the difficult physical and administrative process of acquiring legal male status

What does that involve for women?