Yashahime: Princess Half-Demon: Season 1, Episode 12

1 - 12: Night of the New Moon and the Black-haired Towa

Nikosen was a sage before evil consumed his soul and transformed him into a demon. Konton orders him to kill the Half-Demon Princesses. Nikosen's ambush catches Towa at a bad time, when her demon powers are fading and she is slowing turning into a human.