Season 6 - Random Rhapsody
Episode #128 - Rakugaki Panda no Noroi (らくがきパンダの呪い)
During the Summer Fair, a Chinese merchant shows 3000-year old cursed paintings that are sealed to the public. however, Ranma, chasing his father over some octopus, knocks him into the painting, removing the seals, and releasing the spirits within. while two of the spirits are giant monsters that Happosai, Genma and Soun must combat, and only manage to stalemate, the third is a crudely drawn girl panda, who wants a boyfriend. Ranma must then convince her to return to the scroll before 2am, and they all are released from the scrolls forever!
At first, Ranma tries to play along as the panda's boyfriend, until Nabiki advises him to end the charade early by telling her that a romance between a panda and a human can't last. however, instead of the panda leaving Ranma, she changes into a human. however, the monsters become more unruly, exhausting Happosai and the others, and kidnap Akane. At that point, the Panda decides to leave.