@Not_a_ID
'm pretty sure I was hitting on that with the comment about
(And why the implication of potential very serious harm if someone does something "to soil her purity" as they just devalued all the effort to protect it)
And this is the one spot where the cultural differences might come into play.
Would they value "purity", or would they prefer having her trained in the sexual arts ahead of time? I don't know the answer, and I doubt it could be found on-line.
Both ways could lead to interesting scenarios.
If we posit a Yakuza boss born in Japan but running the syndicate's US operations out of New York (to fit the OPs scenario) with a daughter born in the US or was just a baby when they came to the US who is a bit Americanized.
Being Americanized, she knows about sex at a theoretical lever, but is still a virgin.
On the "purity" side
She wants to have fun, so She goes looking for an older male to provide her with a practical education in sex.
He knows her father is a Yakuza boss and has to put a lot of effort into keeping her out of his pants.
He doesn't know about her father. Is she being watched closely enough by a covert security detail to stop things before they go too far? If not, how does daddy react when he finds out after? Boy will the guy be surprised when he finds out that age of consent and the cops are the least of his worries.
She knows what daddy does for a living. She threatens her security detail with telling daddy they molested her to blackmail them into having sex with her.
On the sexual training side:
She wants to have fun, so She goes looking for an older male to provide her with a practical education in sex. Unknown to her, the man she has picked out and targeted to get her sexual education is actually a plant put in place by her father to provide for her training in the sexual arts and to teach her what her place in the world is, training her to be submissive.
She wants to save herself for a marriage based on love. Daddy (and/or her (unknown to her) betrothed) wants her trained in the sexual arts. She is forcibly removed to a facility dedicated to providing such training.
In either case, the Yakuza boss is either going to keep her under lock and key. Or they're going to try to keep them as far removed "from the business" as possible.
Which is why I suggested up thread that a Catholic school is unlikely.
A high security boarding school that specializes in the kids of VIPs (Government officials, diplomats, the super rich, celebrities, crime lords) would be more likely.