I joke this sort of work is like Neapolitan flavour: it’s vanilla, but it has one or two interesting twists (like you said, the vampire intrigue) to make it more interesting.

And I fully agree with what you said about the characters. Specially their interactions! Like, Kotoyama improved by a lot in this aspect, you don’t see Hotaru or Kokonutsu changing meaningfully because of the other, but Nazuna and Kou do. They grow, a lot like the ones in Sono Bisque Doll. (…that had a better ending. Yeah, I also agree the ending is a bit unsatisfying.)