There was a lot to say about the curriculum at Mistress Xiu's.
Girls from the lowest rungs of society were brought in and given a chance to make something of themselves. Those who graduated would go on to lucrative careers in the employ of the Mistress herself; espionage, assassination, and whatever other dirty work the Mistress required.
Of course, that led to government agents infiltrating the facilities in search of more information on the elusive Mistress Xiu, but guard duty was a regular extra-curricular and any girl who couldn't hack it? ... well, they likely weren't Academy material anyway.
The washout disposal bin out back was always available for those who couldn't keep up, after all.