Not that there's any excuse for it but did they ever show the thought process for why he raped him? I can't remember if we ever saw it from his perspective. I just remember it was so unexpected and seemed uncharacteristic for him up to that point. Unless his "white knight" persona was all fake?
It always bugged me that it seemed so random.
It’s unclear but I think his white knight persona is definitely real if we take how he does stuff like stays at the office into account.
As for the rape think it’s implied to be a mix of him very clearly not being able to hold his liquor/basically completely losing inhibitions. (where we see a couple times where he completely forgets what happens when he’s drunk and asks/does sexual things without remembering) and probably being related to pining away for his coworker and it not being reciprocated
He's super drunk and probably thinking about fucking Saeki dude, like materbating while you're high/drunk. He just thought he rub one out instead of actually raping someone.
This manga is incredibly dark and a well written exploration of how a relationship would realistically develop on a basis of rape, the kinds of people who’d be able for this to happen, and thoughtful portrayals of power and balance. It’s quite heavy and satisfying. I highly recommend it if that sounds interesting to you. Nothing is romanticized or excused between the leads, and it asks a question do when, if ever, their relationship could strike balance after something like that occurred—is balance restored after one rapes the other back? If you learned one was blackout drunk? If the other saves the other from being raped?—it’s a very unique fictional exploration of the subject, and doesn’t offer a clear answer.
That being said THE LITTLE STICKY NOTE NOTEBOOK AT THE END MADE MY HEART MELT A LITTLE THAT WAS CUTE