>>115190It might be that the official mangakas leave eachothers' characters alone (either for respect or because of some rule).
This is why we don't see the Watatsukis, Reisen II, Three Fairies, Clownpiece, Kasen, Kosuzu, Mizuchi or Miyoi outside of their own mangas, aside from some cameos sometimes.
Well Kasen DID actually appear in the fairy manga, but that's the only case of anything like that ever happening that I can remember.