Summary
Gokū reveals that the alien has a tail, just like it used to. He takes it to mean that Gokū remembers him, but Gokū has no idea who the alien is. Gokū reveals that he actually suffered a head injury as a child, which the alien believes would explain his memory loss. Muten Rōshi explains to Goku that his grandfather Gohan explained that he found Goku as a child and that the child was initially violent until he fell into a ravine, hit his head and nearly died. When he survived, his violent temper subsided and he grew into a kind-hearted boy.
In an attempt to restore Goku’s memories, the alien explains that Goku is a Saiyan who was not born on Earth, and that he, the alien, is named Raditz. And he is Goku’s older brother. This shocks the Dragon Team, but Raditz goes further, explaining that the Saiyans are a warrior race that will sell planets to the highest bidder after exterminating the original species. Goku himself was sent to Earth on a mission to kill everyone on the planet. Raditz goes on to explain how lucky Earth was to have a moon, as Saiyans only show their true powers when the moon is full, thus Kuririn, Bulma, and Rōshi vividly remember Goku’s ape transformation.
Gokū, however, denies any of and tells Raditz to leave his planet. Raditz declines as the Saiyan race is almost extinct after the destruction of their planet. They claim that they need Gokū to help them exterminate the species on the planet they recently found. Gokū refuses, and Raditz decides that ig Gokū will not join him, he will just have to borrow his nephew instead, seeing Gohan’s tail as proof of the boy’s Saiyan blood. Violently attacking his brother, Raditz kidnaps Gohan and tells Goku that if he wants the boy back, he will kill a hundred people by tomorrow and place their bodies on Muten Rōshi Island.