Basara Toujou: Basara is Mio's step brother. She doesn't want to see him hurt, especially if it's because of her. She's developed romantic feelings towards Basara due to the fact that he promised to always protect her, no matter who the enemy may be.
Maria Naruse: Maria is Mio's guard and probably the closest living person to her. They love each other as sisters and wouldn't mind sacrificing their lives for each other. They have feelings for Basara.
Yuki Nonaka: They started in a bad relation due to Yuki believing that Mio is the reason that Basara is getting hurt since he's not the same as he used to be due to the incident that happened five years ago so it's unclear how these two really feel about each other. They both see each other as rivals for Basara's affection, and often interrupt each other when one of them is getting too close to Basara. Despite all this, they're willing to put their personal feelings for each other aside and fight together if it would mean protecting Basara.