Lum & her girlfriends are invited to Neptune by Oyuki. There she shows them her new business venture at a ranch of flying sherbets, birds capable of producing sherbet cones from their beaks. Ran convinces Oyuki to let her borrow one, her goal is to make some quick cash selling sherbets on Earth. Unfortunately, the combination of being overworked and a hot summer day has made the sherbet extremely cranky, even from its refrigerated cage. It breaks from its cage and escapes, but not before attacking Ran and Lum, and trashing Benten's brand-new bike by shooting sherbet cones at it. Now it's up to Ran to retrieve the sherbet before Benten blasts it out of the sky, and more importantly, before Oyuki finds out.