Terra1000

Its actually great grand parents. My mistake. The girl is the old King's Yeonjo's mother who started out as a slave(at least in the series). He is very sensitive to his humble origin, hence young Yi san was almost punished for reading that book.

https://www.youtube.com/watch?v=SJABr6b_CvY First night(3:22 to 4:50) between Yi San's great great grandparents. MBC drama, so expect more of this.

Fat chance , you will get a panning shot to the Joseon era wooden ceiling. This is a public channel and very conservative.

I wonder if this Lady Jo is based on the girlJo Hong in the series Haechi. Haechi is the story of Yi San's grandfather accession to the throne. Jo Hong was a slave girl that was helped by Geum(Yeonjo) in the first episode. At the end of the drama she became Seonjo's main "court lady" and wore that green uniform. She loved Geum but the love was not requited. However she was a good character in that series.