Mutio is a water creature created by Zorndyke. Her species is often referred to as the nereids (not to be confused with the mythological Nereids of ancient Greece). Due to their internal organ structure and design, they cannot speak, but each has a very high level of intelligence. The nerieds are Zorndyke's ultimate Unigumo pilots. They live in shallow areas of the ocean and are programmed for strict obedience, even to the point of suppressing their own feelings. Mutio is saved by Hayami early in the series when her fighter crashes and she almost dies. This confuses her due to Hayami being "the enemy." In return, she later saves Hayami when he is in trouble. She also cares for him, and feeds him when he is stranded at one point.