He's part spirit and part feline. However, those 'ears' are not really ears. They're horns, which was an unusual feature of his. Those help him detect many signatures, even electric currents and mana flow. It was strange why he has no ears but he does said that he can still hear us.

How his hair clips were arranged counted up to 40, which means a lot of things. (e.g. The forty days he spent after his family died) We're not sure of his past but dare ask him. He's too serious to blurt it out. Though he is a great use when it comes to weapons....