Man, I don't know why the dojo zombie keeps getting drawn to look so menacing these last few chapters. He clearly just saved the MC and the heroine from being killed by Luz and then gave them the option to join him despite having the ability to kick both their asses and then even after being rejected by the MC (who unlike the girl didn't immediately try to kill him) he's seemingly still not going to kill him and may even help him. There was never even a doubt in my mind that he was a bro after his reaction with the big zombie's decomposition and the first instance of this trend in the first place was when he saved them from Luz so I don't even know what they were going for there.
It's become increasingly confusing to tell whether this guy wants to screw you over or will not. Even now, I'm guessing he wants to have a someone who he can relate to and rely on every now and then, in a delegation sort of way.
@gaylard
I think that's the point. Under normal circumstances the main character and the girl's decision don't make sense however in this extremely fucked up world it's hard to trust people. Even before the fight begin the MC was extremely hesitant about trusting the martial arts zombie. This makes sense due to his past experiences in this universe so far. As for the zombie girl she has clearly given up hope for an actually sustainable and decent life so her reaction wasn't that surprising