I remember watching the first episode of an anime, but I don't remember the name of it: it might have been made between 2014 and 2018. I can recall bits and pieces of it in hopes that someone may know what I am talking about.
There is a male student (the main character) who is new to a school that happens to have demons/monsters in it (it's not a school for monsters, but it happens to have monsters secretly within it). The monsters seem to hide in the shadows of the school. I'm not sure if the main character uses a device or not to see these monsters, but as the new student is being shown around the school he witnesses someone being feasted on in a classroom. I think the main character has a special sense for the monsters. He is also the only one who notices the feast.
Fast forward to the last part that I remember. The main character talks to what I'm assuming is an angel, outside on the roof, I believe. I also think there is a prominent female character who is like the secondary main character.
This is all I remember. Its not High school of the elite or High school dxd but similar in a sense of highschool.