Ugh, where do I start? Everything about this manga, aside from the art, is either mediocre or bad. Characters are your everyday shounen-ai cliché: the stronger, taller guy who makes the initial approach, the shorter boy who is ab-so-lu-te-ly straight, then realizes that the other guy is "a hunk"... you name it.
I think what annoyed me the most, though, is how the plot is rushed and underdeveloped. Sure, it's a one shot, but even against those standards, it falls short. That's because for every moment of conflict in which the story advances minimally, there are a couple of pages in which there is just poor
dialogue and depictions of the characters.
Also, the seme is a vampire that... doesn't suffer from the limitations vampires do. No, seriously, he barely has to drink blood. Why bother making him a vampire, then? That's a waste of every potential source of conflict that stems from a vampire character. Apart from the last three pages or so, the story would work just as well with him being a normal human.
It's a short manga, so read it if you really want to. But I recommend directing your attention elsewhere.