Kyuuketsuki no Libra is a lengthy visual novel by Onomatope* that was translated to English by MiKandi Japan under the name of Libra of the Vampire Princess.
Shuma is supposed to be a regular young youth. That is, until a vampire named Iris abducts him and tells him of his secret birth blood line. She claims that he’s a descendent of the “originator”, and that she’ll now attempt to awake Shuma as the originator. It’s at that time that the ring he received from his mother suddenly starts glowing and prevents him from fully waking up as a vampire. Shuma then also uses that very opportunity to escape from Iris, though his body now craves from the blood of someone from the opposite sex.
He at first however doesn’t want any of that and just wants to live as a normal human being. Unfortunately things seemingly won’t be as simple for Shuma as Iris hasn’t given up and various other parties also start moving. In the end Shuma now finds himself involved in a battle he did not wish for…
Libra of the Vampire Princess
The translation of Libra of the Vampire Princess came to be with the help of a Kickstarter campaign to raise the necessary funds. The first physical editions shipped in May 2017, and are available for sale on the official webstore here. A collectors box is also available, which comes with various physical goods.
A download edition has released on Steam in June 2017.
The official store also contains various other goods like art books, soundtracks, and character goods. So be sure to check those out as well.