Ya Yotsuyu is basically the key focus of what Doma may become depending on what punishment she may get. Her crimes cannot be ignored but the Old Doma government was what created her to begin with as her sadistic nature most likely may never have developed if her life was different.
Dealing with the flaws of the old Doma government may most likely be one of Hien's greatest challenges and true test to see if he can create a better Doma.