Most of the world is blissfully unaware of the evil that has been plotting to kill what remains of the Valkyries. Valkyries were once a team of powerful female witches who were descended from the children of the original gods.
The year now, is 2017, and the evil threatening to destroy the young girls have been active for a while now. Most simply just don't remember the events due to a spell that protects their memories from seeing the truth. The young, new magical girls are ignorant of what evil awaits them. When the six of them end up in hot water, and earn themselves a Saturday detention, they find that there's a lot more to themselves and the school that their parents and the staff are wanting to let on.