High schooler Saya is a friendly amnesiac, who lives in Okinawa with her stepbrothers Kai and Riku and adoptive American father George, a retired Vietnam War vet. One night, mysterious bass violinist, Haji, saves Saya from a monster.
David plans a rescue mission to get George out of the military base but Kai wants to join in on the mission and he's willing to literally fight David over this.
Kai and Riku also arrive in Vietnam. Riku befriends a cute local village girl, who was left crippled by the mines placed during the Vietnam War that the locals dig for to sell as scrap metal.
David, who represents a group called the Red Shield, takes Saya and a team of specialists to the Vietnamese jungle to locate the Phantom's secret research facility and something called Diva. Saya's brothers are also kept there.
Season 1 finale. Saya and the team are ambushed by monstrous feral vampire children. Saya discovers who the boy from the party really is. The Phantom makes his final stand and shows his true form.
In an attempt to understand the supernatural events he'd recently witnessed in Vietnam, the reporter, Akihiro Okamura, contacts Kai and Saya's friends Mao and Kaori to learn more about Saya and her current whereabouts.
Saya and her friends arrive in Russia and take the Siberian Express to their next target. The vampires make sure that they have a very bumpy and bloody ride.
Mysterious hooded figures break into the facility where the vampires are being created and kill every one of them. David and his team are suspected by the Red Shield to be in on the betrayal and are put in mandatory quarantine.
After failing to assassinate suave Solomon, one of Diva's top servants or Chevaliers, the hooded vampires go after another Chevalier - Saya's, hoping that his blood will set them free.
Haji and Saya visit an old burned down mansion. Saya learns more about her past there as well as who Haji actually is and how he came to be what he is now.
Joel's Diary: Saya learns the rest of her backstory from the leader of the Red Shield as well as what went wrong on that fateful gory night in Vietnam 30 years before.
Breaking Shield: Saya and her family spend a nice day in town completely unaware of the vampires' plot against the Red Shield that's been set in motion.
A Boy Meets Girl: Diva's all out assault on the ship that serves as the Red Shield headquarters begins and a horrific massacre that claims even the lives of those closest to Saya ensues.
The Power of Believing: Kai and David try to recuperate after the events of the last episode. Things don't go well. The plans of the evil corporation that created the feral vampires moves to their next phase.
The World Where We Exist: The recuperation continues until a vampire breaks into the countryside house of the family with whom Kai and the others are staying.
Mismatched Feelings: David infiltrates Cinq Flèches, the company behind feral vampires, to capture Van Argiano, the candy-loving scientist that runs it. At an opera house, Saya faces Diva's servants James Ironside and Nathan Mahler.
It Will All Work Out: Saya must decide the fate of Diva's children. Goldsmith returns for one final showdown. The show ends on somewhat of a somber note.