Makarov, Natsu, and the group return bearing news of the impending invasion by Zeref and the Alvarez Empire. With Fairy Tail back together, everyone's hearts beat as one in their resolve to fight! Then, the ghost of Mavis appears, recounting the guilt and power behind Fairy Heart, the lacrima crystal that holds her preserved body. Her tale begins over a hundred years ago, when two desperate individuals, bound by a curse, brought forth an unthinkable sin...