I'm surprised no one has written a review for this yet, as I found it quite a pleasant surprise. Japan has given us some very interesting stories about zombies and demons in the past (the most famous probably being Resident Evil) and this movie is no exception.
Biohunter uses the age old plot device of a virus which leaves the infected with some rather nasty side effects. The show begins by illustrating a woman and her lover, both devoured by the disease. In the case of the young woman, she loses her sanity (and her good looks) while her lover is quite literally lunch. It is a fairly horrific scene, one that really sets the tone for the finale. A lot of movies involving zombies and/or demons choose to depict the former as humans without any sense of self control but don't explore the concept any farther than cannibalism. Biohunter definitely has its fair share of cannibalism, but takes it even further.
The opening scene shows a couple making love only to have the moment disrupted by the 'hunger' of the infected,which sets the tone for the entire movie. The lead character, who has an advanced immune system allowing him to maintain a degree of control over the demonic virus, is a complete gentleman, becoming the opposite when the virus takes over. What appears to be the main theme of the movie - the lead characters seeking out a psychic at his granddaughter's request - is more of a suplot, with the main character's battle against the disease taking centre stage. This man does not trust himself to engage in relationships with the opposite sex, lest his demonic side raise its head and hurt them. The main villain of the movie is a man who has let his demonic side run amok and control him. He is shown as a complete lecher, devouring young women despite his gentlemanly exterior. This theme of predatory human beings who destroy the opposite sex when they reveal their true self is true of the difficulties facing real relationships - how many people in the real world worry that showing their partner who they really are will change their perception? Furthermore, how many people worry that their partner is just using them?
Art-wise, this show is very old, though a lot of detail is given to indivuidual faces and features. Unlike many shows, whose character designs do not vary much beyond 'ugly or attractive', the characters of Biohunter actually have individual ones.
The main weakness of this show is the same as its strength: character development. There are at least four possible main characters of this show and none of them get any particularly decent character development. The movie is open ended and does not give you any kind of conclusion - many of the questions raised within the film remain unanswered without any kind of resolution. You never find out the origin of the Demon virus, whether it is preventable, how it is transmitted etc. I found this really disappointing and felt the movie deserved another hour to explore these concepts.