Can bạn give me your opinion on a story plot I've created?

It's a story I'm going to call "Triplet Dimension."

The story revolves around around our protagonist, Lorelei. She can't call herself popular, but she loves setting fashion trends at her school. She lead a normal school life, until she pulls a "down the rabbit hole" bit. But not down a hole... through a mirror.
After her tumble, she discovers a new world, amazing and completely different, a world encased in light. Lorelei soon meets Serenity, and is completely shocked to hear that Serenity IS Lorelei. Serenity explains that she lives as Lorelei in an alternate dimension, a pure world, called Castela Prisima, and that Serenity was created from Lorelei's positive tendencies and memories.
She also discloses that there is another parallel dimension known as Terrora Diablena, the world of darkness, where another from version of Lorelei lives. This version of Lorelei, named Revia, is evil, and wants her world of darkness to be superior. Her master plan is to be rid of all other worlds to make hers the ultimate.
Lorelei and Serenity must do what they can to stop Revia. But can they save their worlds before they're destroyed?

Tell me what bạn think, I don't mind CONSTRUCTIVE critisism. Thanks!

[Characters below, from left to right: Serenity, Lorelei, Revia]