Nau is a water deity introduced in the anime Sengoku Youko. Initially appearing as a mad god driven by mind control, Nau attacks a village under the orders of the Tribe of Void in an attempt to steal the Jewel of the Thousand Wonders. After being defeated in battle and freed from that influence, Nau becomes a loyal companion to the main group. The character has no memory of their past, including their original name. The name Nau is given by the human girl Tsukiko, chosen because the spirit habitually ends sentences with the sound nau. This verbal tic becomes a defining trait. As a water god, Nau's abilities are tied to water. When near or consuming large amounts of water, spiritual power increases dramatically, causing the form to shift and grow into a mighty divine beast. Even in a smaller, more ordinary appearance, Nau can alter shape at will. In terms of personality, Nau is gentle, empathetic, and deeply loyal to those who show kindness. The character prioritizes the well-being of companions, often acting with warmth and a desire to be helpful. Beneath a calm and sometimes stoic exterior lies a strong need for belonging and acceptance, stemming from the lost memories and the isolation of being a spirit without a past. Over the course of the story, Nau develops close bonds with Senya and Tsukiko, sharing with Senya the experience of having no recollection of former life. From an initial role as an antagonist, Nau grows into a steadfast ally, using water-based abilities and the transformative power to aid the group in battles and protect those who have become like family.