Mizu is a rogue Shinigami in the Human World. He has not attached himself to any humans, and he despises Kira. He believes Kira is a threat to all Shinigami, seeing as most of the criminals, who Mizu enjoys killing with the Death Note, are being eradicated.
He is mostly a wild type of person, often getting in fights with other Shinigami. He seems to be a friend of a Shinigami named Assari, but the status of their relationship is unknown.
Mizu is a rarity among Shinigami. His skin color is pure black, and he has completly white clothes, and a black belt. He looks almost completely human, if not for his skin color.