I think a "please give it a chance!" description puts off people more than the shoujo demographic; folks can be pretty contrary like that. (Plus the fact that a lot of us like shoujo and stupid love stories, so being negative about them changes our first impression from "a mystery/crime shoujo, huh" to "something that a guy who thinks shoujo is bad would like.")
Replacing the note with one saying "please don't add the romance tag, as the main focus of the story is on the detective/thriller aspect" would probably work better if you're trying to keep people who dislike romance from judging it prematurely.
That said, the first chapter is pretty good. Whenever a mystery series invents a reason for the sheer volume of murders happening around the protagonist, the detective is often the one with the "death follows them wherever they go" explanation/lampshading; the way it's integrated into the story here is nice.