Nishiki
A “half-baked” Fuuma ninja who infiltrated the prison looking to avenge her clan, but was convinced to abandon this way of life by Soramaru. Volume 4 extras show that Nishiki, like Shirasu, is an atrocious cook.
She is considered “half-baked” because she was unable to complete her training. Thus she has only half of the Fuuma’s characteristic white hair and purple eyes.
Nishiki is eventually taken into the Kumo household and develops feelings for Soramaru, which drive her to betray her clan and help defeat the Orochi.