This story is a sequel to A Certain Magical Sunset
Sunset and Twilight, recently graduated from Canterlot High, have accepted the opportunity to attend University in Academy City, honing not just their intellects but their magical skills as they become embroiled in the plots within plots at the heart of the Academy and beyond.
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.
It's recommended to read prequel first as it does provide the background for the setting and characters.