Elemental Heroes Anthologies (aka their backstories)

Here's the Elemental Heroes aka thr past of the main characters.

Elemental Heroes is a Gacha Series made by Laury Sempai about Pamela whose is in her first day at her job as a Librarian, stumbles across a magical book on the shelves. Turn out this book isn't ordinary; this book chose her as the new Guardian of the Elements where she have to protect her from the dark forces who will use it for greater evil. And by doing so, she needs to gather all the Elemental Heroes to fight off against the Dark Knight. With the help of Usagi/Light, Luke/Flame, Ruby/Ocean, Roy/Lightning, Nicole/Energy, Carmen/Lover and Molly/Nature, they'll work together to protect the world from the forces of Darkness and defeat the Dark Knight and the Villains of Darkness and Despair once and for all and bring peace to the world.