Shinobu No. 23

Based on shinobu from Demon Slayer

A sekirei with black hair and purple eyes that wears a butterfly like kimono ( I think) her power is poison which she uses in conjunction with her sword although she can use poison without her sword

Her wings a light purple with dark purplish veins ( dark purple represents the poison)

Her norito is: by the poison of my pledge I shall envenom all of those who seek to harm my ashikabi