i'm not gonna argue why you liked it, i mean hey, we all different kinks XD but Chiaki loves Masafumi, right? why would he rape the other girls then? AND WHY WOULD HE PUT A GLASS CUP IN HIS ASS ? ┗( T﹏T )┛tho i do wish there was a sequel to that, where they reconcile, and have intense sex, but with NO GLASS CUPS.
Those are some really good questions! Since Chiaki is royally screwed up, he prolly never admitted to himself being in love with Masafumi. Even when his desire for Masafumi warped itself into some really gross stuff. Maybe the isolation in prison from most human contact, finally shoved his human feelings to the surface. All he has then, is that name scratched on the wall.
Well despite most of the "wtf" comments I am seeing about the last chapter, I really liked it. Chiaki loves Masafumi in his own twisted way from the very beginning. I strangely found it romantic that Chiaki never saw what he was doing as rape. c: I wish there was more to that story.