Dragon Ball Z Special 2: Zetsubou e no Hankou!! Nokosareta Chousenshi - Gohan to Trunks

Thirteen years after Androids 17 and 18 begin devastating Earth, nearly every great fighter is dead. Gohan has grown into humanity's last real defender, fighting a hopeless war while training young Trunks, the son of Bulma and Vegeta, to become a Super Saiyan strong enough to survive the ruined future.

Trunks wants to join every battle, but Gohan understands how much one reckless mistake can cost. As the androids continue slaughtering survivors for amusement, teacher and student are pushed toward a confrontation neither is ready to win. The loss that follows leaves Trunks with a choice: surrender to the future he inherited, or find a way to reach the past and prevent this world from ever being created.