My only advice would be to avoid forcing the PCs into it. To force a PC to do something requires being more powerful than them and keeping an eye on them constantly. Otherwise they just punch you or skip town. But if you can follow the PCs anywhere anytime and beat them with one hand behind your back... why do you need them? Just go out and police the city yourself with your super ninja powers.
It's not always a bad idea to put the PCs under someone's thumb if it makes sense, but this scenario in particular seems ill-suited for it.