1800 years ago...
There exists a realm where humans do not exist, but demons. Demons, deity or not, dangerous or not resides in the dark realm where humans could not comprehend.
One day, demons landed on human world's earth, poison seeped into earth, crops wilt, and thus humans finally acknowledged the threat of these unknown creatures, demons.
Demons washed the land with blood, tainting the sky in darkness, strikes fear in hearts of many humans, making them believed that the world is going to end.
5 years later...
Humans formed a community to hide from demons, and they all fled into caves. During the night, despite it's dark and dangerous, the stars in the sky still shine brightly. Stars became a symbol of hope, and they started praying to stars.
Another 5 years passed. Humans finally discovered a method to tame demons, which is by signing a contract with them. Signing a contract was a huge deal to people that time, demons no matter what, took way too much life from them. People hated them, those who sided with demons shall begone.
Contract signers are banished from the community, they left in a group of 20 people, they all have a demon with them. Only people who are brave enough to bet their soul to the demon earns its respect and thus, whenever they die, their soul is to be devoured by their demons. They still have large numbers with them.
The group grew stronger day by day, destroying demons wherever they go. Eventually, they earned the people's trust and they earned their social status as the leading party of the community.
They built a fortress over the years, vanquished countless demons and finally they are able to keep the demons at bay.
Of course, sacrifices had been made, out of 20 demon summoners, only 12 of them remains. The leader is now known as the emperor, while the rest are known as guardians or dukes.
They civilization grew into an empire, or better known as Hoshido, City of Stars. The numbers of demon summoners increased, and they are respected as guardians. Those who misused their powers is to be subjected to execution.
This took 30 years, until a man with white hair claimed to be a "disciple" of the demon realm's gate keeper. He is powerful enough to kill 4 of the demon summoner guardians. He can perform rituals to "release" demons from their "seals", granting them even more power.
In other words, he's evil. Things get worse until there are only 5 demon summoners remaining in the nation, including the emperor himself.
The emperor confronted him alongside with his guardians. They created a force field to bind his movements. His demons are far more powerful than the emperor's.
The emperor had no choice, but to summon the four heavenly gods to destroy him. This requires a lot of spiritual energy, thus the four guardians started the ritual, and summoned the powerful spirits to attack the white haired man.
"My name is Baku, remember it well." Is what the last remaining summoner who came back alive told the people. He ascended the throne and led the people well.
Those who are said to be related with the demon summoners are said to have immense spiritual power. Demons mysteriously vanished from the world. According to the second emperor, they performed rituals to seal the demon realm's gate.
Back to present, year 2017...
There is no proof about that, even archeologists failed to find any evidence that demons existed. This tale is now only told as myth in the Hoshido nation. No one actually believed in demons now.
21th of December 2017, 23:59 p.m.
On top of the Hoshido's central government building, it was pitched black in the night. A flash of lightning flashed over the sky, revealing a figure with white hair, standing on top of a lightningrod pole effortlessly. He smiled, just like he is listening to something.
"Oh, this must be very interesting... Hahaha..." He said to himself.
"Oh, it's time to let them remember my name again, Baku." His arc of smile became wider.