Saotome Ranma, Wiseman, Book 1

Under the name Wiseman, Saotome Ranma has been the guiding force of Nemesis for nearly a millennium. Now 1,000 years in the past he and his Black Moon Clan family have a chance to change a world's future for the better as they work on fixing their own present. Ranma and Usagi on the other hand must deal with future versions of and unpleasant revelations about themselves.