OK, the brain has decided that if he controls the Dojo it'll put him on
the path towards taking over the world.

He shows up (before Vol 1) claiming to be Genma Saotome, and this is his
son Ranma (Pinky), who's suffering from a mild transformational curse at
the moment.

"Oh he wants Akane."

"Oh, definitely"

"You like cute little animals, don't you?"

"Well, you're in luck, he's half mouse."

"Me, marry that rodent?  Never!"