Urusei Yatsura (1981)

S1E1 I'm Lum the Notorious!

The episode kicks off with a baseball match where Ataru gets walloped by a flyball from left field. Afterward, he’s taken home, only to learn that he has been selected to face the champion of an invading alien army in a game of tag that will last ten days. If he loses, Earth faces an invasion, but victory means the aliens will retreat. Initially, Ataru is reluctant to participate until he catches sight of the alien champion—none other than the stunning Lum.