Well, Kinugawa was proven an idiot when he decided to step into an obvious trap. The place was even labelled for him. I guess rage and overconfidence are truly a lethal combination.
Two to go. I have the impression Ajiki won't be easy. His brief outburst last chapter and his declared lack of interest in people indicate he might be exceptionally sadistic, with far more brains than Kinugawa.
At this point, I'm more interested in how Maria will deal with Okaya. My hunch is that the way to mess with him is through his family, specifically his mother.