I commented quite a few chapters ago that Setsuna's real reason for training Akita was for developing her ideal DV dom daddy.
This chapter makes me think that maybe I wasn't that far off, even though I was joking.
Also, she really likes tanking punches to the face without flinching. Maybe some chapters in the future we'll find out that she's actually a robot learning to be human, and her conclusion is that being human = violence, thus her quest for ultimate violence, therefore true humanity. At least it would explain how she can repeatedly get clocked on the nose and just make a face like

afterwards
By the way, I find it really funny how after getting his shit beaten up, Akita just looks like he's sleeping (very comfortably, even, given that he's supposed to be malnourished, thirsty and just got Tiger Knee'd right in the mouth).