Sheila Helman

Rance IX
Rance discovers Russian in a slave trading caravan that his party took out, and in exchange for sparing the girls around her from his sexfest, he demands that Russian be his slave for the remainder of his adventure. Russian accepts and becomes a slave of Rance. In battles, she is capable of using healing magic, and uses a sling to attack enemies. However, she is initially completely inept at housework, nor does she possess much general knowledge about the world. This however changes as she quickly learns the ropes with Kentou Kanami's help.

Trivia

 * SPOILER!

She is in fact Siera Helman, empress and the powerless ruler of the Helman Empire in disguise.