While the book is titled "Segunda," the main character is Segundo. He is a young boy who is the only one who remembers his past life after a mysterious event that wipes out all other memories in their village. He is tasked with saving his sister Flora, who has been taken by a creature called the "Eater."
So, while Flora doesn't exactly "save" Flora, he is the one who actively works to bring her back and ultimately saves her from the Eater.