Nagare is a yokai known as a Mizuchi. Originally a dragon, he was stripped of his power and became a Mizuchi. The reason was apparently because he "went on too many rampages," which he personally accepts as fair enough. Nagare's body is covered in hard orange scales, and he has sharp claws on his fingertips, though he can make them disappear using spiritual power. His shining silver hair is long and beautiful. He possesses the power to manipulate water, hardening or softening it at will. His body fluids also have the power to heal injuries. His left eye shines gold, but his right eye is a hollow socket with no eyeball. Long ago, when rumors spread that "a dragon's eye cures all diseases," he was targeted so relentlessly that he got tired of being chased and just threw it to someone.

Because he was sealed and his power drained for his past rampages, he is currently unable to leave the marsh in the deep forest where he lives, spending his days in relative peace.