No, not the teacher who is a succubus. She's just another Christmas cake virgin, same as practically all female teachers in anime. (P.S. Spoilers.) I'm referring to the male teacher, who is perhaps the rarest of anime creatures: The adult male lead in a harem comedy. Or, more specifically, he is an adult male anime character who behaves like a goddamn grown-up despite being the lead in a harem comedy.
Demi-chan wa Kataritai (Demi-chan Wants to Speak, localized as Interview with Monster Girls) certainly is a harem comedy. After only three episodes, one character has already openly expressed her affection for Tetsuo (a biology teacher in his early thirties), a second character stated the same privately, a third character just isn't being up-front about it, and the fourth simply hasn't been properly introduced yet. Nevertheless, he's sincere when he claims his interest in his non-human students and co-worker is purely academic, and calmly interacts with them without any of the usual carrying on you get in harem comedies. This is a sharp contrast to, say, Potato-kun in Seiren who is insufferably spastic as he struggles with his adherence to the Otaku Virtues. (It turns out Seiren is...not a good show.)
Nevertheless, Demi-chan is still a harem comedy, and it's pretty clear the teenage vampire, dullahan, and "snow woman," as well as the adult succubus all (or eventually will) pursue Mr. Takahashi as a romantic love interest. This has caused some viewers to express (at least on the Twitter) a bit of discomfort and/or displeasure with the direction the show is taking, even though it's all but assured there will be zero development on any of these routes. C'mon, it ain't that sort of show, okay. Nobody is going to bend Kyouko over a kotatsu while her head is in a different room.
There is one additional thing: It seems some viewers feel inspired to critique the show from a considerably more "woke" perspective than I use, but I think this tendency also results in the adoption of a perversely opposite position from what was perhaps intended. In particular, I've seen a few people discuss Kyouko, the dullahan, as a disabled character. To me, it is openly racist to presume dullahans are presumptively inadequate or compromised compared to humans. Treating dullahans as dullahans instead of as "disabled" humans is the difference between treating ajin as minorities instead of treating them as "abnormals," in my book, even if you're using the politically correct term "demi" instead.