There is a missing mission with Kasha. She appears as the boss in a mission taking place in the same 'area' as Winds of Ruin and Dawn of Hope.
I've been looking for this particular mission for half an hour to farm for her core but I swear it's been deleted in the last week or something because it's gone.
You fight upwards a tower through some ninja before exiting the building out a destroyed wall down two roofs and into the courtyard where you fight her and a couple of yokai.