It was made clear that she was crazy rich when she was showing off an AmEx Centurion card in a prior chapter, since those are invitation-only cards that they only give to people with net worths in the millions.
If she were related somehow to yakuza, she would just snap her fingers and that would be the last we ever see of the delinquents.
She wouldn't have that much cash to throw around unless she were related to a very-very-very high ranking yakuza.