Fairy Tail Vol. 10 (manga)
SHADOWS OF THE PAST
Erza Scarlet is the most kick-butt woman wizard in Fairy Tail, but in the past this indomitable fighter was . . . a slave? Now she finds out that her old companions have completed the evil device they were forced to build while held in slavery: the Tower of Heaven. What’s more, their wicked master requires a sacrifice: Erza!