Mao  

, マオ

Mao is a half-beast princess from Bestia who has animal ears and fangs to identify her heritage. She leads the mercenary knighthood Weiss Ritter and left End-Earth in search of Zero on Earth. In doing so, she unintentionally brought Souma and Kureha back to her homeworld. Her soul blade is called "Beast King Sword Lion Kings Flame Dance" and has fire properties. It's Soumas preferred sword but not his Ultimate. Later in the series, it's hinted that Mao and Souma have feelings for each other, though nothing comes to fruition until the end.