Is Urusei Yatsura Movie 3: Remember My Love hentai?
No
Rated PG-13 (Teens 13 or older) on MyAnimeList and not tagged as Hentai.

Movie · 1985 · 1 episodes · PG-13 - Teens 13 or older
Action, Adventure, Comedy, Drama, Romance, Sci-Fi, Shounen
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)
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