This piece is an alternative ending to the "weakness cautery point" storyline (or possibly "Hiryuu Shouten Ha storyline") that runs in volume 13 and 14 of the Ranma ½ manga. I'm not sure what numbers the Viz translations have.
The ending of that storyline struck a strange chord within me. It was the first time that I saw Ranma give up. Because that's what he was doing when he thanked everybody for their help and left. Trying to run away after a defeat like this was, of course, not very mature, but it still moved me. Of course, Ranma couldn't really be defeated in the original manga, but I couldn't keep from thinking about what would have happened if the last piece of the map was really lost.
Since I never saw the Viz version, the dialogue up to Ranma's departure was based on the original Japanese with some educated guesswork and the help of a dictionary. Quite a bit of it is made up from whole cloth, though.
Sebastian