300 Years ago, in the year 2025 of human AD, angels came to the world, and they punished mankind in the name of the God of Crime and Punishment.
The sin king angel symbolizes the seven deadly sins: pride, wrath, envy, sloth, gluttony, lust, and greed, bringing great havoc to the world.
At the same time as the angels descended, the plague defined as the "angel virus" was just like the Black Death in the West a thousand years ago, which took away the lives of nearly one-half of the people on the earth, and two-thirds became deformed "angels" that raged like monsters, threatening the remaining humans.
In a short period of time, the entire earth gathered people with strong antibodies against the Angel Virus to form an angel hunting group to launch a resistance against the source of this catastrophe - the Angel of Sin.