It's not really open ended though...You can see Messiah walking out with 'the brute'.
I guess you could argue that that's just master's prediction, but come on—There's no way he was getting with his bat shit crazy friend.
Both of them are batshit crazy. WTH.. whom does one choose? Guy A who pays Guy B to rape you or Guy B who ACTUALLY rapes you? In all rational sense, nobody should be chosen but this is Harada. Harada likes playing mind tricks along with sick plotlines, that's why plenty loves her work. If this wasn't open-ended then it will just be another ordinary plotline where protagonist expectedly falls in simple lovey-dovey with his rapist. Harada doesn't do that.
Am I the only one who thinks that Messiah's choice was open-ended? Like, Harada intended it to be vague and confusing since revealing who it was didn't necessarily matter anyway ’cause both guys are terrible people. I like that it makes the reader's imagination choose between two choices which are virtually one and the same. Good troll!