Even though she could not see Mark, Medusa could more or less guess what he was thinking.
She sneered with a small mocking smile at the corner of her mouth, "Indeed. As a Hunter, she is an absolutely perfect being. In more ways than one, there are probably not even ten hunters who are more perfect than her for this role. She has the talent, the skill, and the training. So I accepted her but that doesn't mean that girl is alright in the head."
The criteria for becoming a hunter were both strict and loose in a certain sense. They didn't care how sane someone was or what kind of morals they had. All that mattered was if their morals and sanity would affect the job they were assigned to do negatively or not.
With such criteria, there was no way Medusa would have refused someone like Tsubasa who had been trained as Hunter since she was a child and already killed many supernatural creatures and evil spirits. She was far too experienced and valuable to ignore and shun.