Comic adaptation of the specials by Toei Animation:

On Planet Vegeta, a Saiyan named Kakarrot is born. His father Bardock soon obtains the ability to see the future and discovers that Freeza has turned on the Saiyans. Bardock confronts him, but Freeza destroys Planet Vegeta and the Saiyans as Kakarrot is sent off to Earth. And so, the story of Dragon Ball begins…

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The artificial humans have left the future in shambles, killing all of the Z Warriors but two… Gohan and Trunks. As the two battle to save future, Gohan is killed and Trunks finally obtains the power of the Super Saiyan. However, even that isn’t enough to defeat such evil, so the young boy travels to the past in search of hope.