I'm sorry i forgot about this, but does anyone know whether the Jade Oni says anything when you are about to defeat him? I haven't completed Mooshu in a while, so i don't remember.
"Fool! Did you think I would give up this shell so easily? I am not like the other Oni. You have woken me only to make me stronger! This land is mine!"
And after you've defeated it:
"Nooo...!"
I don't think it says anything while you are battling it.