Not much is notable about the lecherous Ataru Moroboshi, but his extraordinary bad luck sticks out like the horns in an alien's head. When Earth is threatened by a fleet of alien invaders known as the Oni, Ataru is selected to represent humanity in a duel against one of them. It's a stroke of rare luck for Ataru that the duel is in fact a game of tag, and that his opponent is Lum, daughter of the Oni's leader, who places her personal dignity above victory—as Ataru finds out by seizing Lum's bikini top and with it, victory. However, misfortune kicks in again when Lum mistakes Ataru's promise to marry his girlfriend, Shinobu Miyake, as the desire to wed Lum herself, and decides she rather likes the idea. Wielding her influence as an alien princess, she moves in with him. Forced to deal with the consequences of his womanizing ways, Ataru must balance his crumbling relationship with Shinobu while keeping Lum happy, all the while flirting with every woman he meets.

When aliens known as the Oni threaten to invade the Earth, they promise to leave under one condition—a randomly-chosen human must win a one-on-one game of tag against Lum, the beautiful daughter of the Oni leader. The "lucky" person selected happens to be the lustful and unlucky high schooler Ataru Moroboshi. Given 10 days to attempt to grab Lum's horns, Ataru realizes how impossible the challenge is as he is faced with Lum's extraterrestrial powers. Motivated by a promise of marriage from his childhood friend Shinobu Miyake, Ataru manages to catch Lum off guard. He mistakenly grabs hold of her bikini top first, but he eventually achieves his true goal. Although the game is over, Lum misunderstands that she is the one whom Ataru wants to marry, and she decides to move in with him. The poor student constantly tries to shake off the clingy Lum while doing his best to reconcile with his desired fiancée. After Ataru's heroic feat results in such a disastrous outcome, it is questionable whether luck will ever be on his side.

Second season of Urusei Yatsura (2022).

Lum doesn't need much assistance going ballistic when everyone in Tomobiki gets an invitation to Ataru's wedding... and she's not listed as the bride! It seems that some 11 years ago, Ataru played "Shadow Tag" with a young girl named Elle and won. Unfortunately, Elle was yet another Alien Princess; and on her planet, if a boy steps on a girl's shadow, they have to marry.When Elle's emissary comes to make arrangements, Lum redefines the term "the atmosphere was electric," but to no avail: a force-field now protects Ataru from her high voltage love-zaps. Lum's friend Benten suggests a pre-emptive wedding, and they proceed to abduct Ataru and all of the wedding guests, and the stage is set for the shotgun wedding of all time!