Male protagonists gets closer to a few girls, that are demi-humans, including succubus, dullahan (head separated from the body), snow woman and a vampire girls, all of which have a positive relationship to that main character. If you think of another trashy harem, prepare to be rick-rolled.
Everything in this anime have the potential to be trashy harem, but instead ends up the most wholesome “harem” I have ever watch. We have a school teacher interested in a bunch of girls due to their demi-human nature, but his interest is actually genuine research interest instead of being a lolicon. We have a succubus teacher, but instead of ending up seducing our main protagonist (or any other boy), she sees her “aphrodisiac” power as a problem. We have headless woman, but we discover that is a problem, if you do not have a neck and must carry your head with your hands all the time. Or a vampire, that have to deal with the sun. Or a snow woman avoiding everyone because she is afraid that she can freeze and hurt people around her. In this slice of life you will explorer the problems that such mythological demi-humans appear to have and how to handle it and make friends along the way. It is a wholesome slice-of-life / school-live with really responsible adult teachers. I am so used for harems (many girls likes a guy) to be trashy that I could not imagine having such a premise could end up in a wholesome enjoyable anime, showing me how good the high-school life was (not actually, real life is not an anime, but we do not watch anime to represent what is real-life but what we want it to be).
Animation is good enough to never see anything wrong, but it does not stand out.
The sound acting is really good and express the character feelings well, but the dubbed version lack of subtitles/labels for text messages, which could be a problem sometimes, but luckily those are not too often to lose track of what’s happening.
Overall, this anime surprised me in a positive way. If you feel nostalgic about school (assuming you are not in a school right now), this is a decent anime to watch. It might not make you laugh, but it will make you smile.