Maha

Little is known about Maha (at least from watching only the anime) but Tsukasa refers to her as a female so it can be assumed Maha is female.  She never speaks - at least out loud.  She seems to speak to Tsukasa but we hear nothing- yet Tsukasa can.  She has the ability to phase in and out of fields and often is hanging out in Aura's domain.  Who she is trying to help - or work for is often unknown, but Maha is more important than we initially assume.