You've got the Seek Out Brother Tosai quest, from Bujo in Kaineng Center. If you abandon that quest the Am Fah will be enemies again and you should be able to cap.
If you're unsure of his location, check the map on that link you provided.
And if I right now have finished that mission?
I did her quite a while ago, but ability I want to get it now. Bujo no longer gives me missions, and the one and only that I can catch is the one with Master's Degrees of Corruption.