Lavi is a demon attending the magic school as an exchange student. The queen of devildom sent Lavi and her twin brother Favi as a part of a talent exchange program between the human world and devildom, hoping they would learn the delicate ways of human wizardry.
While she is exceptionally talented at defense spells, she technically doesn't understand to cast them. She just intuitively uses them for brawls she often gets into. She hopes to become the ultimate fighting champion of the world much to the dismay of the devil queen (who is, by the way, funding her tuition).
She loves her brother but gives him a hard time because... well, because it's her brother. But she won't think twice to risk herself to help him in any situation.