When Louise did the summoning ritual, she hoped for beast of great power and grace. Something that would erase any doubt that she too would be a great Mage. She'll just have to make do with the Chosen Undead of Lordran.

Louise has always been known as a Zero, incapable of casting even the simplest of spells. It's her chance now to prove herself at the annual Springtime Familiar Summoning, but she'll have to prove herself to more than just her peers if she doesn't want it to end in a sea of black flame.