The Mystery of the Birth of a Woman - Ubume no Kai

...What is noteworthy about this form, which is handed down in the Tohoku region, is the motif of the transmission of great power. This is similar to the story of the "Ubu-me no Kai," in which a man was asked by a female slayer to take care of a heavy child and was then transmitted great power. There are also many legends that say that the female slayer was a local deity, or that the female slayer always appears on the night of Little New Year. Taken together, this motif of the transmission of great power can be said to be based on the theme that those chosen by the gods are given supernatural powers by undergoing trials. ...

*Some of the terminology that refers to "Ubujo no Kai" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…東北地方に伝わるこの型で注目に値するのは，大力伝授のモティーフである。これは産女に頼まれて重い子どもを預かったら大力を伝授されたという〈産女の怪〉の話と共通する。産女は氏神であったとか，産女は決まって小正月の晩に出ると説く伝承も数多くみられ，総合すると，この大力伝授のモティーフは，神から選ばれた者が試練を経ることによって超能力を与えられるテーマに基づいているといえる。…

※「産女の怪」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報