Dr. Raichi, the last known survivor of the Tsufuru race the Saiyans wiped out generations earlier, returns to Earth to finish the job against Son Goku and Vegeta, the planet's remaining Saiyan warriors. He seeds the atmosphere with machines pumping out a deadly gas, and Goku, Vegeta, Gohan, Piccolo, and Future Trunks have 72 hours to track them down before the gas kills every living thing on the planet. This side-story OVA sits outside the main Dragon Ball Z continuity.