This story is a sequel to Sunset Shimmer - Six Friends One Heart
School over, their friendships stronger then ever in the aftermath of the fiasco that was Anon-a-Miss, the girls get their first real look at their World, and Universe beyond CHS and Canterlot. It's bigger, wilder, and more wonderful then they ever imagined...
The goddesses of creation have found their champions - Two Sisters from another Mister, fresh from the memories of their battles to overcome their own demons, bound by their love for one another, their friends, and their desire to help others overcome their darkness.
This story is a cross-over between the Shimmering Hearts verse from Six Friends One Heart, and the magical wild verse from A Certain Scientific Railgun and it's companion stories. The insane magic in Railgun, psychic and otherwise, along with the intrigue, drama, and friendships in those stories made this a natural fit with Shimmering Hearts.
Please note that it is not necessary to read the prequel to enjoy this story, though it does provide some background for the setting and characters.