Our characters have heart diseases. Perhaps it was genetics, perhaps it was some other reasons. With only days to live by, they're beginning to accept death. On one fateful night, both have the same dream. An "angel" healed their heart condition as well as giving them ability to see people's "heart". The healing has a condition: to ensure that their heart would be healed permanently, they must collect the "dew" shed by "flower of heart" within people close to them. Said "flower" was the thing which the angel had bestowed them the ability to look at, which no one else could see. Unfortunately, all of the people with said "flower" was still in the form of buds, and they must help to make them bloom in order to collect the dew.

Vampire, ruler of the night. Contrary to popular belief, Vampires don't die from sunlight, onions, or holy water (although sunlight weaken them so much). After a hunt, the victim will turn into a Vampire themselves, although with weaker constitution and more vicious hunger than the ones who changed them. Third-generation Vampires, bitten by Second-Generation Vampires who were themselves bitten by the Originals, was deteriorated so much that their victims no longer turned into Vampires, but died instead. The Vampire society strive to hide those death from normal human's knowledge, keeping themselves hidden in the shadow.

Humans who knew the existence of Vampires banded together as Hunters. Vampires couldn't be killed easily except on their weak spot, which varies from Vampires to Vampires. The only thing the Hunters could do was keep on attacking until they could strike that weak spot, either by chance or by observing the Vampires' actions.

Within this chaotic world, rumors floating in Vampires society that some certain Hunters were moving from town to town, decimating thousands of Vampires using only a small number of personnel. Only one, to tell the truth, because those so-called Hunters were not human after all...