Ubume

Ubume was a Demon exclusive to the Third Light Novel of Demon Slayer: Kimetsu no Yaiba. She was a member of the Twelve Kizuki, having held the position of Lower Rank One (の) at the time.

Multiple decades ago, Ubume was a human by the name of Yae and lived a normal live along with having a husband.

Abilities and Powers
Overall Abilities: As Lower Rank 1, Ubume was the strongest Lower Rank at the time and the closest to matching the strength of the Upper Ranks. She was able to stand her ground against both Sanemi Shinazugawa and Masachika Kumeno, two powerful Demon Slayers trained with their respective Breathing Style, the Wind Breathing, even killing one of them.

Supernatural Abilities
Blood Demon Art:

Trivia

 * Ubume is not Yae from Giyu Tomioka: Gaiden as the kanji for each of their names are completely different.