Touka is an Evenkuruga mononofu (warrior) who serves Lord Orikakan. After Orikakan is murdered by Yue, she swears vengeance. After seeing the respect which Hakuoro pays to the fallen emperor, she pledges fealty to Hakuoro to serve as his bodyguard and, omitted from her spoken oath but firmly kept in her mind, bear him a child. In the game, she pledges fealty because Aruru and Eruru convince her that Hakuoro is a good person. True to her clan's nature she obsessively follows this oath. However, even though it was part of her oath, she fails to have a baby with him because Karura tricks her into thinking that she would become pregnant by drinking Hakuoro's semen (this only happens in the game). She fights using a slim sword which she combines with her astonishing agility to execute swift and deadly attacks.
Touka is a member of the Evenkuruga tribe, a small clan living near the steppes, who are blessed with such extraordinary fighting abilities that many of them have carved their names in history. They are a deeply moralistic people and side with good and fight evil in the name of justice and honor. This is mentioned several times during the anime. At the end of the series she works with Karura as a wandering mercenary and follows Hakuoro's request to act as a protector of the weak.
She is sometimes seen as the comic relief, mostly due to her over-protectiveness of Hakuoro (as seen when she picks through every piece of a fish, searching for poison, before letting the new Emperor eat it) and her feminine side, which conflicts with her warrior-like persona.
In Itsuwari no Kamen she is seen working in Karura's inn, Hakurou-kaku in Yamato, where she was formerly a yojimbo bodyguard but chose to become a regular worker due to the city having good security resulting in her not having anything to do as a bodyguard.