After being involved in a fatal accident, Junmin and her friends sees the world a bit differently. Differently as in, weird black things floating around them. But, what they didn't know was that those black things were:

Agma: Demons

Until one day, they encounter a powerful demon. Scared to death, they didn't know what to do but, run. Running like their lives depended on it, which did, they encountered another demon and this time they were trapped. Praying that it would be a quick and painless death, they waited to die. But, instead they were saved by two people; one female and one male. After calming down, Junmin and her friends were told they were not ordinary humans, they were:

Agmaui Sashin: Demon Reaper

Agma Ripeo: Demon Reapers

These 12 girls do not have a lot in common except for one thing; They were all orphans. Does the demons have to do anything about it?