Mizukagami (水鏡, Mizukagami?, lit. Water Mirror) is a mushi that lives in stagnant water. It blends in with its surroundings and resembles quicksilver, or liquid mercury. In its basic form, the Mizukagami cannot move around on its own and requires a mineral-rich body of water to survive, so it covets a physical form that can freely search for what it needs.
Symptoms
When the Mizukagami reflects the image of an animal on the surface of the water, it comes ashore and tries to imitate the animal's appearance by following it around. This weakens the original animal little by little, which in turn strengthens the Mizukagami's corporeal form. Eventually, the original animal loses its solid form and the Mizukagami replaces it.
Weakness
At the moment when the Mizukagami tries to replace the original animal, it becomes visible. If its image is reflected back to it during that moment of transition, it will revert back to its basic form.