this is such a bad manga
it starts with a total tragedy setting because of what it seems laziness; by killing everyone close to the protagonist, author has no need to come up with their characters, sorta like how some romcoms have the parents always traveling abroad to save themselves the hassle from writing them in;
then there is the sensei x student; If you're not going to make a compelling story about the taboo, why even bother with this pairing? I'm assuming is ALSO laziness to prevent a relationship from forming;
If a relationship doesn't form, you don't have a romance manga; what's left? comedy? this manga isn't funny, it's just tragic;
then there is the "character just goes along with what's happening"; so you entered a maid cafe (fairy, whatever) and didn't just ask the staff about your sister... why?
overall, this is a 3/10, waste of a good artist in a nonsensical story