Nephilim is a term used for people who are the offspring of the sons of God (the Angels) and the daughters of the humans. These children of the two species grew up to become legends, and many hailed them as heroes or gods. However, because of this action, God saw the Earth as a corrupted and vile shell, thus is the reason why he eventually limit the lifespan of the humans to 120 years, and summoned a great flood so that it would wipe out every living thing on the face of the world. After the great flood, not much is left about whether the Nephilim survived or ceased from the world. Fortunetely, the Nephilim bloodline survived for the next several thousand years later, which was passed down to those who would eventually join the Order of the Saint. Kidomaru, Marie, Dimitri, Hakuro and Rose are one of the few humans who's bloodline was inherited from the Nephilim of ages passed. However, with the awakening of the Nephilim bloodline finally blossoming after a long milennia, it can be assumed that almost half of the children from the human race will be born as true-blood Nephilims upon childhood.
The Nephilim's abilities and powers are widely known throughtout the world as great heroes, some even believe them to be like gods. They have superior strength, endurance, speed, intelligence, and many other physical and mental capabilites that surpasses that of average humans. Their healing factors are also high in speed, and their lifespans have been determined to be twice to three times that of normal humans. Another unique trait that Nephilim possess are that they have a single angel wing on their back that signifies them as half-angels. Each of these single wings are unique in color and property, as they can be on either the left or right, and can vary in color and form (an example would be that Hakuro's right wing is azure blue with gold-tipped feathers, and Dimitri's left wing is pitch-black with silver-white tips on the feathers).
When the great flood had passed, the Nephilim bloodline was passed on for future generations to come, and the strong bloodline would only awaken after many generations had passed. Upon the late 20th century the bloodline of the Nephilim was reawakened, and the children born from these families were hailed as their ancestors were from the time of Genesis. They were identified as true-bloods, as there was no single drop of human blood in their veins from birth. However, because these children were born with superior abilites they were feared, hated an evied by many who were normal, thus the Nephilim descendants joined the Order of the Saint to gain recognition and praise as heroes in God's service.