She is the current-ruling queen of Tres España and the vice-president and treasurer of the student council of Alcalá de Henares, Tres España's academy. She is also part of the Eight Great Dragon Kings as the owner of one of the Mortal Sin Armaments, Akēdia Katathlipsē.

Spoiler

Despite pretending to be an elf, she is just a half-elf (who are heavily discriminated in Tres España). She was saved as a child by Felipe Segundo during the Battle of Lepanto, though he didn't know that the half-elf girl he saved then was Juana, until she tells him before the armada battle. To save her position he denied her, rejecting her confession as a lie to stop him. She looks up to Felipe and wants to repay him for saving her.