Setsuna

is the deuteragonist in the anime series Hanyō no Yashahime.

History
Setsuna is a half-demon demon slayer who works under Kohaku. She was separated from her older twin sister Towa when they were both 4 years old but was reunited with her after traveling to the future with her cousin Moroha.

She seems to have difficulty believing Towa is really her sister. She has a calm, unflappable personality much like her father, Sesshōmaru. She also seems to have some sort of sleep-related childhood amnesia.

Trivia

 * While it is known that her father is Sesshōmaru, her mother's identity is so-far unknown.
 * Unlike most other hanyō, including her paternal uncle Inuyasha, Setsuna does not have any visible, physical indicia of being a half-demon, such as dog ears. She does, however, have a mokomoko that trails from her right shoulder and splits into two in the middle of her back.
 * Despite being an Inu-hanyō like her uncle Inuyasha, she and Towa seem to age at the same rate as humans.
 * Setsuna's name, like that of her sister Towa, is homophonous with a time word, "moment" or "an instant". This is likely an allusion to the fact that both sisters travel through time. Additionally, it’s also ironic significantly share with warlords Setsuna no Takemaru, a movie-exclusive character.