Earth faces a huge crisis. Aliens want to invade the planet. Humanity's only hope rests with Ataru Moroboshi, who was chosen to represent Earth in a one-on-one duel with the aliens' chosen warrior. There is only one problem with this plan. Ataru is a womanizing, stupid loser. How in the world can he hope to succeed?

Selected to fight for the aliens' right to take over Earth is Lum, their curvaceous, bikini-clad princess. Luckily for Ataru, the duel takes the form of a game of tag. All he has to do to win is grab Lum's horns. Not so luckily for him is the fact that she can fly and, being a normal human, he most definitely cannot. Just when it looks like Ataru is destined to fail, his girlfriend Shinobu makes him a promise: she will marry him if he can win.

The encouragement is enough to motivate Ataru to succeed. But just when it looks like Earth is saved, he faces another problem. Lum misinterprets something he said and thinks that they are now married! Urusei Yatsura follows the unlikely relationship between the lecherous Ataru, the beautiful alien Lum, and all of the strange people they meet along the way.

Broadcast between episodes 21 and 22, the Spring special was a 1-hr show with 2 parts. The first part, "Urusei Yatsura All-Star All-Out Attack!", was a series of outtakes from the preceding episodes and recaps of the first 21 episodes. The second part, "The School Excursion! Run, Kunoichi!", was an original episode, but not part of the ongoing series.

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!

[Source: AniDB]

Not all is normal in Tomobiki, even by its standards. The students have been preparing feverishly for the first day of the student fair, which is scheduled to go on the next day. However, problems arise when some begin to notice that the next day simply will not come. As the students begin to try to find the reason for the problem, their beliefs about reality and the world of dreams are challenged.

[Source: Anime News Network]

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]

The adventures of Lum, Ataru, Ten, and all the gang from Tomobiki continue in an assortment of new – but no less weird – stories.

Watch as Lum, Ataru, and Shinobu encounter a rabbit-clad youth, enter the Room of Destiny, and get a glimpse into their futures in "Inaba the Dreammaker," or see Ran's plans to use a sherbet cone-producing bird to open a sherbet shop one hot Tokyo summer go terribly awry in “Raging Sherbet.” Ataru has yet another bad experience with Lum's cooking in "I Howl at the Moon".

[Source: Anime News Network]

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]

The Urusei Yatsura story comes to a climax in this animated retelling of the final Manga story (although not the final movie). Lupa, yet another one of Lum's fiancés, arrives on the scene, and Lum and Ataru have to repeat their game of tag in order to prevent the Earth from being destroyed.

All Ataru has to do to win is say "I love you" the three words he has steadfastly refused to say to Lum. Will he admit his true feelings and save the Earth? Or will his pride doom it to destruction?

[Source: AniDB]

Lupica, another one of the legion of space princesses that all seem to have found out about Earth in some tour book, appears and abducts Ataru!

But Lupica isn't after Ataru for his great looks or charming personality (because he doesn't have either). Lupica's goal is the greatest love potion in the galaxy, which she intends to use to induce her sweetheart to tie the knot. To get it, she needs the possessor of the greatest lust in the universe...

[Source: AniDB]

The story is from manga volume 23.

When an alien race known as the Oni invade Earth, the chronically unlucky and unapologetically lecherous Ataru Moroboshi is selected as humanity’s representative in a duel for the fate of the planet! His opponent is Lum, the Oni’s very pretty princess, and it’s only thanks to Ataru’s unscrupulous behavior that he’s able to scrape out a win in a treacherous game of tag against her. Ataru thinks he’s had his lucky break at last, but when Lum takes a shine to him off the battlefield, the conflict follows him home as Lum invades not only planet Earth, but also the womanizing Ataru’s love life!

[Source: HIDIVE]