Ranma’s fight with Saffron destabilized the Yggdrasill system causing his and Saffron’s data to be lost. When Skuld and Urd fix the system and restore the files they mistake parts of Saffron’s file for Ranma’s changing him into a goddess. This is Ranma learning her goddess powers and fighting off evil demons. (Ah! My Goddess Crossover, Tenchi shows up later.)