Gowen Manilla is the main character of the "Story of the Amnesiac Vampire" (『忘却の吸血鬼編』) storyline in Kuutei Senki. Originally, he was a human. However, on one day, after waking up, he found out he had lost all his memories. The only thing that he remembers is the image of a girl, whose face is covered by a hat. Not only that, he loses control of himself unless he drains other people's blood from time to time.
To regain his memories and to search for the woman, Gowen begins his journey all over the world with the help of his assistant Shade and a helpful little ghost Anastasia (Nasu), drinking blood of women he meets to survive. Even though he's originally a very kind hearted person who wants to avoid violence as much as possible, he occasionally turns into an evil vampire and violently rapes them.