The phrase "harsh mistress" refers to a situation or person that may be demanding, strict, or difficult to please. It implies that dealing with or being under the influence of that situation/person can be tough and unforgiving.
Sentences with «harsh mistress»
Continuing with the roots of the company they announced two light novels, based on the wildly popular Attack on Titan property; Attack on Titan Before the Fall: Kyklo Arc and Attack on Titan: Harsh Mistress of the City. (manga.jadedragononline.com)
Attack on Titan: Harsh Mistress of the City takes place just after the beginning of the Attack on Titan manga. (manga.jadedragononline.com)
Science - fiction author Robert Heinlein didn't invent the phrase, «There ain't no such thing as a free lunch,» but his novel The Moon is a Harsh Mistress helped to popularize it. (fortune.com)