That woman wasn't just randomly hired, she knew everything it seems, I don't agree to randomly torturing woman, who would, but Shira was right in what he said "if you wanna hate someone hate your boss", they are trying to stop the guy, if they feel pity for everyone who the guy hires then they are fucked because they sure as hell won't feel pity for them when they accept the job.
Shira is probably coming back for revenge now and that's not good.
At this point I don't really care about Kagehisa, I'm not sure what he is doing now but it seems like he isn't raiding dojos anymore and is trying to move forward and I mean, that's good, he's doing a good thing now, sure he did bad things to get there but that's the past, he's doing good now but if MCs end up killing him I'm not going to be "oh no, all the good things are going to waste", nah, not really, really couldn't care less about what happens to him, I'm on MCs' side now, revenge? Help the country by killing a mass murderer? Whatever, either way is acceptable.