Past Arc

Early History
The planet on which the main story occurs was once the domain of angels. However, a nuisance of a god went on a rampage for the sake of training, which resulted in the loss of all of the world's angels other than Sariel. Alone, Sariel continues her mission of protecting the planet's primitive lifeforms.

Some time later, a family of dragons appears on the planet. Sariel is indifferent to their presence, so long as they do not threaten the native creatures. While the dragons wanted to rule the world, Sariel's presence forces them to be docile. Many years later, a young dragon named Güliedistodiez tries to kill Sariel, but instead falls in love.

Tragedy of Tetmaia
The country of Tetmaia develops new kind of bomb that has the power to rewrite the terrain. For an unknown reason, Tetmaia drops this bomb in a region that dragons lived in. In their fury, the dragons completely annihilate the country, and are only prevented from eradicating humanity by the intervention of Sariel. This event increases the humans' sense of awe and fear towards dragons.

Dragon Infant Abduction
A dragon infant is abducted by a criminal organisation after being exhausted by a battle against the captors. They do a series of tests on the infant, from which it is seen that despite being composed of conventional minerals, dragon scales have structural properties in excess of what would be normally expected.

The dragon's upper echelon sends a young dragon who had recently reached the realm of the gods, Gyurie, to oversee the human military's rescue operation under orders to only act if the infant's life is in danger. Fustrated, Gyurie lashes out, but he's stopped by Sariel, who completely negates Gyuries attack while preventing any damage to the surroundings. With their vast difference in strength clear, Gyurie meekly watches while the infant is rescued.

Vampire Outbreak
Vampires predate the creation of the system. The initial vampires were an unaging species that spread by modifying other's through magecraft and were hunted by dragons. They were considered to be a non-native species by Sariel, and therefore not worthy of protection. They lost the sanity of their previous species when converted, although a Sariel-worshipper named Foddway was the one exception to this rule.

Creation of the System
In ancient times, a human named Potimas Harrifenas learned how to tap into the MA energy of the world in his search for immortality. Potimas' technology quickly spread throughout the world, forcing the dragons to wage war against Sariel and the humans in order to stop the collapse of the world. They were unsuccessful, so instead departed the planet, taking much of the remaining MA energy with them.

With the planet's collapse imminent, Gyurie sought aid from D. D proceeded to create the System, using Sariel as the central energy conduit and information processor. The System forces all the world's souls into a closed reincarnation cycle in which each soul is stripped of its accumulated energy at the end of its life.

Situation After System Activation
The first Demon Lord and Ruler of Pride, Foddway, was a vampire that converted a significant proportion of the world into his kin. After he was killed, the vampires were hunted into extinction.