Beautiful space alien princess Lum invades Earth on her UFO, and unlucky Ataru Moroboshi's world gets turned upside down! Will Lum become Earth's electrifying new leader? Or will Ataru somehow miraculously save Earth from space alien onslaught?

Lum is finally going on another date with Ataru! But while she's waiting for him to show up, an eccentric young man arrives to claim that he fell in love with her at first sight. Normally Lum wouldn't care, but Ataru is late for their date! Later, Mendo receives a mysterious New Year's card that says, "I know your secret." Mendo doesn't have any secrets, but that doesn't stop him from vowing to track down the culprit! Now he just needs to find a way to analyze the handwriting of every guy at Tomobiki High...