It seems that when Lum was born, a postal screwup resulted in a witchy friend of the family not getting an invitation to the celebration. The witch put a curse on Lum, that she would never be happy with her True Love. 

In the present, a new Amusement Park has been built in Tomobiki, and opening day finds the whole gang sampling its pleasures. At a magic show, however, Ataru gets turned into a large pink hippo-potamus, FOR REAL! 

When Lum attempts to track down the magician that transformed her Darling, things start to get very weird, very fast! 

(Source: AniDB)

Strange things begin happening in Tomobiki Town... 

When a great cherry tree, "Tarozakura" is cut down while Lum & Co. are making a movie, Lum loses her horns-and her powers! Thus begins the strangest and most lyrical of the Urusei Yatsura movies...

(Source: AniDB)

Maeda is a new student in the Teiken High School. He stutters when he's nervous and he's rather clumsy. He gets noted immediately because he hits a teacher during the entrance ceremony. Some clubs search to enlist him as they see in him a force they can use to get even with other clubs. But Maeda is a loner and has only one dream: becoming a boxing champion.

A pilot film streamed on the anime studio Toei Animation's website. The female leads in the film are dressed as various famous robots in Toei's anime catalog—the girls are personifications of robots in the Gaiking ("Gai-chan"), Magnerobo Ga-Keen ("Gacky"), and Superhuman Combat Team Baratack ("Bara-tan") and the newly added character is from the anime Planet Robot Danguard Ace. (Source: ANN)