Beatrice

Beatrice (ベアトリス) is a mage of Re:Zero. She is one of the greatest wizards if not the greatest, residing in a room with magic books only to be accessed by portal magic through doors

Plot
Beatrice is the one who heals Subaru after the first arc when the first reincarnation loop is over. Also, she can use all elements of magic especially the Yin. She was traumatized by her past, hence, she loves to pet Emilia's Spirit Cat.