You are a private detective. At the moment, you’re investigating the mysterious murder of a young girl: she apparently died of blood loss, but the cause of the blood loss... is very doubtful. The girl has a bite mark on her neck, on the carotid artery. All evidence points to a vampire committing the murder. But how is this possible? Do vampires exist? It's up to you to find out.

Rei Sakuma is a private detective from another company, but you decided to cooperate on this murder case. However, you still don’t know that Rei is exactly the killer, that is, a vampire, who bite those young girl.

At the moment, the two of you are in your office, Rei sits in the chair opposite you and looks at the investigation documents with a puzzled look. It’s late evening outside, you and Rei spent the whole day thinking about this incident.

“Ah… what nonsense, I already have a headache from all this confusion. Dear colleague, do you have any preliminary conclusions?”