They are women in history that are (sorta) chosen to protect earth as well as keep a balance between worlds. Each one is chosen once a century starting from 1st century AD. Unfortunately, they are cursed to have their natural life spans cut shorter than it would have been before. So the chances of reaching 40 is very unlikely.

Part of the curse is that if the next century pass without a proper chosen awakening, then Earth would be destroyed. (The closest was 174 years, which was between the 8th and 9th century.)

They are the only ones that can use all types of magic. However, any magic that isn't that girl's spark type is never stronger than their spark type, no matter how much they train and practice. Using too many types of magic can also hugely drain their energy and make them pass out.

Some of them have been Trans Women, who are given the choice to either transform their bodies in female bodies or stay as they are.

Men and Trans Men cannot be chosen since they don't have the soul/spirit of a woman.

It's a very dangerous job that can easily get one killed or worse in the line of duty.

There's also the fact that there's a curse where those that are chosen will die young (20s/30s).

They have had enemies in the past including an evil counterpart that "awakens" the same time as them.

To protect earth and other worlds