She was framed for murder by her brother-in-law
Before getting married to Adam, there was one family member who certainly didn't want Kono to join the Noshimuri. Adam's brother Michael framed Kono for the murder of Victor Asanuma in an attempt to break up the couple and strengthen the family's bond with Yakuza. To make matters worse, he attempted to kill Kono when things didn't go according to plan. That could sure make holiday get-togethers awkward!