Myotara-ten or Myotara-tennyo is a Japanese god who is a guardian of Shinto and Buddhist deities, good people and children, and also a god of exorcism and matchmaking.
Tradition says that a mountain witch called Yasaburo-baba (hag), who once committed every evil such as devastating lands or eating people in Niigata Prefecture, later became this god.
There are various theories about Yasaburo-baba. One of the theories is that the mother of a man called Yasaburo was transformed into a hag, and another is that a hag bit Yasaburo's mother to death and transformed herself into his mother; and much more. Some say that Yasaburo really existed. Kurotsu family which really exists in Yahiko-mura, Nishikanbara-gun, Niigata Prefecture, has a man named Yasaburo KUROTSU as its ancestor.
There are also various theories about how Yasaburo-baba turned into the god: she had turned over a new leaf by the efforts of sojo (the official Buddhist priest in the highest position), or she felt ashamed of herself for having done evil deeds and became a believer in Buddhism personally, or local people enshrined and worshipped the hag as a god to suppress her misdeeds; and so on.
Myotara-ten is enshrined to Myotaraten-do hall in Ipponyanagi, Takahata-machi, Higashiokitama-gun, Yamagata Prefecture, and it is said that whooping cough will be cured by offering Ema (a votive horse tablet) with a picture of a chicken on it to the shrine.