She Is The Law

In South Korea, traditionally mother-in-laws wield an enormous amount of power over their daughter in-laws.  There are even shows and a web comic about it:

"Audiences were shocked when actor Min Ji-young had to go to the salon because her mother-in-law insisted she look her best before visiting their house for the first time. 

Or when former flight attendant Park Sae-mi, who is currently in her final month of pregnancy, cooked food at her in-law’s house while her husband was away on business. As she worked hard preparing a meal, her mother-in-law prodded, 'When are you going to have a third child?' 

Kim Dan-bin must face her mother-in-law day and night because they run a restaurant together. All three wives, despite the fact that they are members of the family, are being abused in many ways."

 This sounds like a total nightmare, of course.