Kyuuketsuki Ha Shinzo No Yume Wo Miru summary:

"He'll do it with anyone who asks, you know. Even me."Hisato, a vampire, has been a foster parent and the centre of affection for Shuri, a university student for the longest time. Hisato will kiss, have sex, even say words of love if one wishes for it, but... Wanting to become the "soulmate" that Hisato has been yearning for, Shuri has been eliminating people getting close to Hisato relentlessly—the never ending humans who offer their blood and body to Hisato and seek pleasure from getting their blood sucked.