Humanity's dominance over the Earth came to an end when the meteorite "Abyss" struck the Earth.
Waves emanating from the Abyss transformed some humans, granting them
superhuman physiques, immortality, incredible regenerative abilities, shapeshifting abilities, and the ability to drink blood.
They were dubbed
"Vampires," after the monsters of the past.
All vampires, under the orders of Mother Vampire, set out to completely dominate humanity.
Humanity was quickly defeated, and people were forced into human ranches known as colonies.

The story is set in Colony 214
, the East Asian Governing Region. "Kudo Liquaria"
was newly appointed as the colony's ruler and to capture Avalon Island, a base for humanity fleeing from rule.
A few days before Kudo's arrival, the colony was destroyed in a human rebellion.
Kudo's sister, Elfina Liquaria, who originally ruled the colony,
also went missing.
Elfina had disappeared just before the rebellion broke out in the colony.
To gather information and find clues about his missing sister, Kudo infiltrates Avalon Island.
Transforming into a human, he is accompanied by his robotic caretaker, the "Able Servant."