When the Oni threaten to attack Earth, they agree to depart if a randomly selected human wins a one-on-one game of tag versus Lum, the lovely daughter of the Oni chief. The "fortunate" individual chosen is lusty and unlucky high schooler Ataru Moroboshi. When given 10 days to capture Lum's horns, Ataru discovers how hard the task is due to Lum's otherworldly abilities. Ataru manages to catch Lum off stride with the prospect of marriage from his childhood buddy Shinobu Miyake. He initially snatches her bikini top by accident, but he soon achieves his intended purpose. Despite the fact that the game is done, Lum believes she is the one Ataru desires.