Moroboshi Ataru is possibly the most unfaithful, unlucky and lecherous idiot to have ever been born, but for some reason Lum, a tigerskin-bikini clad alien package of sex appeal, jealousy and electricity has fallen for him. The misadventures of these two stubborn teenagers are spiced up by a veritable entourage of eccentric characters. Among these characters is Shuutarou the richest boy on the planet, Shinobu a superhuman schoolgirl, Ten a fire-breathing baby, Sakura a powerful and very beautiful priestess/school nurse, Ran a cute and psychotic alien vixen with a split personality, a gender-bending martial artist, Benten an alien biker chick, Oyuki the ice queen of Neptune, Cherry a deranged monk, a giant ghost cat and many other lunatic personalities; aliens, humans and non-humans alike interact in endless hysteria in a town named Tomobiki.