Not only was the plot all over the place, I'm disgusted by how many idiots here are scream...

Can I get an AMEN! The plot was terrible!

Actually that was due to the fact that he was given drugs and aphrodisiacs. And in other mangas when you get those you have no memory but you crave sexual release or you are in big pain. Well this is not quite true (there are drugs like ruffies but they do not work exactly like that, especially aphrodisiacs). In mangaland they do exist thought and if the protagonist was drugged someone must "assist" him in order not to feel pain ╮(￣▽￣)╭

yeah no, the person that’s drugged is under the influence of the drugs so it’s not consensual at all. Anyone in their right mind wouldn’t lay a hand on an obviously drugged person.

Yes. But the thing here is "context". Remember please you are in the land of Yaoi Mensing self lubricating assholes, no-prep sex, static roles in sex and my personal favourite "what the hell is communication". So rules here get warped and it's alright as long as you understand is just fantasy that doesn't translate to reality. There was just one manga I can recall that actually took "consent under drug influence is not consent" and said so explicitly (btw it was one hell of a stupid generic manga that I really didn't expect to see that).
As Merenda said, drugs don't act like that. Those drugs that we often see in mangas are fictional and highly exaggerated like most yaoi rules.
So giving here the status of rape to what happened here without any of the emotional baggage it carries it's problematic for starters.