Hi, i'm looking for this manga that's about this boy who is killed protecting this princes...

Hi, i'm looking for this manga that's about this boy who is killed protecting this princess, and then brought back to life as a vampire (or something). And these vampires don't suck blood, but souls. And to keep down these urges, they use a special flower or something like that. Sorry for how vague this is, but anything helps ┗( T﹏T )┛