A career werewolf, Ouka is a fearsome fighter. She originally meets Shugo and Rena at a special cherry blossom festival, when coming to see them and Mireille. Shugo takes an instant attraction to her, especially in wolf form as he "loves puppies." Ouka is all too happy to respond to Shugo's affections in kind. Like Shugo, it is not known how far she really wants this interaction to go, though Ouka appears to milk it for all its worth. As a character, Ouka has two alternate shapes; a white wolf that can use human languages, and a tall, pale, voluptuous human the age of 20, with wolf's ears. In real life, she is an extremely nerdy-looking student who has a part-time job as Mireille's tutor. Her class type is Werewolf, due to The World expansion pack available to very strong players. Ouka's one interest is challenge; she is all the time seeking "a worthy foe." This has led to some suspicion that if Shugo fulfilled his sister's expectations of heroism, Ouka would deem him such a foe and kill him.

The second volume of A.I. Buster mistranslates her name as Orca in the english version.