Ouka Tsukishiro is a character from the Japanese Inyouchuu Shoku franchise, which includes the animated work released in English as Harem of the Hell Spawn. She is a young woman with very long purple hair that reaches her waist, red eyes, and blunt bangs, and her standard design includes a school uniform, knee-high socks, a hair ribbon, and a neckerchief. She is the twin sister of Kikuka, and the two are distinguished by eye color, with Ouka having red eyes and Kikuka having blue eyes. The sisters are closely linked throughout the material and also appear together in several other games by the same studio, such as Kowaku no Toki and Hanamaru 2.

Rather than belonging to a single story, Ouka appears across multiple entries in the franchise. She holds a supporting role in Inyouchuu Shoku: Ryoushokutou Taimaroku, is elevated to a main character in the expanded Kanzenban version of that work, and also appears in the related manga Inyouchuu Shoku: Ryoushoku Shima Taimaroku. In the Harem of the Hell Spawn adaptation, she is presented as a combatant who fights using banishing seals made from paper strips, which she throws at her enemies in battle. Her fighting style is built around these thrown talismans rather than direct physical combat.

Her role in that story is that of a supernatural specialist confronting the hostile forces of the setting, but her mission is interrupted before it can be completed. Shortly before reaching her objective, she and a companion are caught in an ambush, and she does not get the chance to finish what she set out to do. As a result, her appearance in the adaptation centers on an effort that is cut short by the dangers around her, leaving her abilities demonstrated in combat but her larger goal unfulfilled.