well - we know she's a succubus, and traditionally they have powers that would turn the actions you're citing into something much more sexually charged than they would be if this were just some "conventional" hot girl assaulting a boy that one of her contemporaries likes.
To you first paragraph, I'm of the opinion that what we're seeing is effectively the "progressive/conservative political dichotomy" but played out with yokai/supernatural beings. You have the platform pushing for forward-thinking ideals and ideologies where everyone lives in harmony and overcomes whatever "innate characteristics" would prevent a cohesive intermixing of peoples into society; and you have the counterpart--those saying "this is our nature and to deny it is to deny ourselves". Emu effectively belongs to the former, and Rinka represents the latter (at least going by the person she's talking to in the flashback, and her seeming disdain for Emu's way of going about things).
That's not to say that it's pleasant, but we also have that one classmate who's shamelessly going after Emu all the time--saying things like "she's a succubus; you can't help but dream". So as I remember you saying last chapter, there's a definite chance that we're being shown a much more gritty version of the reality at play in this setting, and not just some silly fluffy romcom between an otaku succubus and a boy who is overly-thoughtful about how he comes across in his crush on said succubus.
And if we're being honest--this is sort of what I would expect out of an entity that literally survives on sexual energy, placed in a modern setting where she's told "you can't just do that to people", coupled with the jealousy of adolescence and watching someone "appearing to be winning on easy mode".
I could write something about "they're not human, so expecting human norms and morals is folly", but I realize that's a slippery slope to go down that excuses just about anything and so I won't touch on that until the author drags us across that line.
I honestly am just impressed that the author went there, and didn't have either Emu walk in before Rinka did anything, or just have her pull back at the last second getting flustered.
At a certain point I'm going to get "fuck this"-frustrated by the lousy job this series is doing in explaining its lore. Maybe the next chapter will fix it or something. But you can't just say "succubi are more attracted to men" and leave it there, because that's nothing. Wow, they're super-heterosexual? They have lower standards when it comes to men? They have stronger sexual urges? Lower sexual self-control?
I'm already pissed that we had a whole introduction in the first chapter that made it seem like succubi were just another human-like species that operated according to biology as we currently understand it. And then several chapters in you suddenly go "Hey check this shit out: MAGIC!!" at us? And we still don't know the extent of the magic powers they have? Or whether it's magic at all?
Why DON'T we know the political landscape? There have been plenty of places to mention it, like when they briefly mentioned restrictions on succubi in the sex trade. If there is a tradsucc faction, you probably want to introduce the concept before having one assault the MC.
What is sexual energy? What's a "good relationship" - an extended or romantic one? Are there adverse effects on the man? What makes a "good man" for a succubus? Does it coincidentally align with desirable traits in japanese culture of like, tall, well educated, rich, good family, nice face? If so, why?
All of these questions could have been answered easily in a single page in the first chapter. They're things the main character should know. And knowing the answers would strongly influence how we as the audience view what we're seeing unfold.
I'm not like, surprised that a succubus is assaulting a human boy. I'm also not demanding she face consequences, because haha holy shit c'mon, a manga dealing with rape in a considered, realistic, or "good" way? As a medium, it regards rape with about the same care and importance as it regards throwing car batteries into the ocean. And I'm pretty sure that up until recently, a woman couldn't even legally commit the crime of rape against a man in Japan. Like, "three years ago" recently.
No, I'm just pissed that I got excited for what seemed like a smart, well-thought-out, well-built and -integrated world that was going to talk about social issues by reconciling fantasy and reality, and then this is where we wind up.
In fact, I'm
disappointed that there's nothing succubus-exclusive about this assault in its motivation or execution beyond some kind of horn-powered stun gun being subbed in for an electric one, blackmail, drugs, etc. It's boringly human and something we've seen in manga where it's played out exactly like this dozens of times - right down to having Emu burst into the room just before things get really serious.
I thought maybe the series aspired to greatness, despite the (admittedly a little funny)
T gag. Instead it seems pretty content in the muck of cliche.