Vampire: carnivorous, supernatural undead creatures with enormous strength and abilities that survive by feeding on the living. Their hunger will be fulfilled by flesh and their thirst will be subsided by blood. Humans are their most nutritious source as their famishment will be easily fulfilled and last longer.

The first creation was made by a deity, using an unbreakable necromancy spell and blood of Nidhogg, blood-sucking dragon/serpent that reside in Niflheim. The cursed turned a mortal man into a Renatus; a term for reborn man; and made him immortal with flaws that come from Nidhogg's blood.

Master: The first generation of vampires.

Parent: A higher generation vampire that turned a lower generation, which is called offspring.

Offspring: A vampire that is turned from another higher generation vampire. Their strength and abilities are lesser than their parent.

Feeding: Vampires requires to eat meat as it is the main source of their protein to take care of their muscles. Even though they are undead, the body is still running normally so blood alone won't be enough to fulfil their protein needs.

Drink: Vampires can't drink from each other as the blood will be poisonous to them. However, the offspring can drink the blood of their parent and vice versa, although the parent will require more blood from the offspring to be satisfied. The reason is that the venom inside their body is the closest match to each other so it won't be poisonous. The host that had been drunk will require to drink more as they technically just lost some blood of their own.

First-generation vampires are able to drink the blood of younger generations as their body has more venom than the latter, making them more resilient and able to resist poison. However, they will get malnourished if they keep on consuming from younger generations as their body requires much more nutrition than the younger ones.

Eyes: When a vampire turns its eyes, the glowing colour of its orbs also determined its generation and power. Red in their kind means the amount of poison that is inside the body. This means, the redder the colour of the irises is, the more powerful the vampire is.

White-coloured orbs vampires are the lowest and weakest of their kind. But despite being the weakest, they are still stronger than any normal human being and they still have abilities as a vampire.

Abilities: The intensity of the power is determined by generation. The older generation will have more power than the younger ones as they have more venom in their body. The lowest vampires only have basic abilities whereas the highers have more, depending on their generation's sequence.

Basic:
- Regeneration
- Eternal life/Immortality
- Enormous strength
- High sensitivity on their senses

Intermediate:
- Higher sensitivity on their senses
- Superhuman speed
- Turning

Elders (First Rank and currently, only one person has the ability):
- Elemental manipulation
- Burn one's own body into ash and regenerates back immediately (Teleportation)

(The origin of some of the abilities will be explained later as the story progress.)

Desire and Promise: Once a desire is fulfilled, a promise is made. Once that exists, the promise that is made to a vampire, especially elder ones, are absolute. It is forbidden to ever break them, except the pledgee side decides to free the pledger from the vow.

Companion: Two vampires that vow to intertwines their lives together eternally. If one of them died, the other will eventually follow. It requires a certain ritual, called Union, to become each other's companion.