The series revolves around the adult life of Mark Feuerstein when she lived in an apartment in the building where he grew up. His parents' apartment, his brother, his sister's wife and their child's apartment are located in one place, where he has made numerous attempts to set boundaries with his parasitism, but the family has another view.
At least he (Feuerstein) gets to work with his writer wife, Dana Klein,, with whom he created the show. (They say based on their lives. I say, condolences.)
Just about every plot turn on 9JKL can be seen coming, and the parents are so gratingly oblivious and interfering that it's hard to get invested in the plight of Josh, or any other character.