"Urusei Yatsura" is a comedic science fiction anime series centered around the chaotic and often absurd relationship between Ataru Moroboshi, a lecherous and unlucky high school student, and Lum, a beautiful and temperamental alien princess from the Oni race. The story begins when Earth is threatened by an alien invasion led by Lum's father, the leader of the Oni. To resolve the conflict, a game of tag is proposed, with Ataru randomly chosen as Earth's representative. Despite his selfish and womanizing tendencies, Ataru manages to win the game by accidentally grabbing Lum's bikini top, which she interprets as a marriage proposal. This misunderstanding binds Lum to Ataru, and she moves into his home, declaring herself his fiancée.

Lum's arrival disrupts Ataru's life, as her alien technology, supernatural abilities, and fiery jealousy create constant chaos. Ataru's persistent attempts to flirt with other women, particularly his childhood friend Shinobu Miyake, often lead to comedic confrontations with Lum, who frequently electrocutes him with her electric powers. The series explores a wide array of episodic scenarios, blending slapstick humor, romantic misunderstandings, and science fiction elements. Recurring characters include Ataru's long-suffering parents, his rival Mendou Shuutarou, a wealthy and arrogant classmate, and Benten and Oyuki, Lum's alien friends who often visit Earth.

The narrative frequently incorporates absurd and fantastical elements, such as time travel, alternate dimensions, and encounters with various supernatural beings. Despite the comedic tone, the series occasionally delves into more heartfelt moments, particularly in exploring the evolving dynamics between Ataru and Lum. While Ataru initially resents Lum's presence, their relationship gradually develops into a complex bond, with Lum's unwavering affection contrasting with Ataru's ambivalence. The series balances its episodic structure with recurring themes of love, loyalty, and the unpredictability of human (and alien) relationships, making it a foundational work in the romantic comedy genre within anime.