Lord Nan Dou, also known as Nanto Seikun (ナントセイクン), is a demon in the series.
Nanto Seikun is the Japanese name for Nan Dou Xing Jun (南斗星君), the Six Longevity Lords of the Southern Hemisphere in Taoism. An opposite to Hokuto Seikun, Nanto Seikun is attributed to the element of fire, appearing as a youthful person in fiery robes. Prayers to Nanto Seikun allow a person to prolong their life, averting any disasters that can lead to death and change their luck or fortune.
"The Taoist deification of the southern Dipper, part of the Sagittarius constellation. Like Beidou-Xingjun, he governs the life and death of men, but he has stronger associations with life and is worshiped as a kinder god."