Boy/boy vampire adult

Maintaining that Yui's blood is special, bishie Seiya monopolizes his childhood friend slash prey, incurring the intrigue of other vampires in school and I want to taste your blood, too trouble for Yui. Yui believes that Seiya, trailed by the inevitable fangirls, will never fall for her, but “I can't stop my heart from racing when he kisses me.

Marlo has a problem. On the night of the full moon, this half-werewolf, half-vampire undergoes a mysterious and terrifying transformation:
He turns into a girl.
Desperate for a cure, his parents call on Doctor Vincent, a long time family friend.