Urusei Yatsura Movie 6: Itsudatte My Darling

Space princess Lupica kidnaps Ataru Moroboshi because he possesses exactly the quality she needs: an unmatched capacity for lust. Only someone like Ataru can obtain the galaxy's ultimate love potion, which Lupica plans to use on Rio, the tofu seller she has loved since childhood.

Lum, Benten, and Oyuki chase after them, but the potion soon causes more trouble than Lupica intended. Ataru becomes caught in its effects, Lum's jealousy explodes, and Lupica must confront the fact that magically forcing Rio's feelings cannot solve the distance created by their different social positions.