Trunks departs back to his timeline, leaving the Z Fighters to prepare for the attack in three years.
The boy reveals he is the son of Vegeta and Bulma , having traveled 20 years from the future. Dragon Ball Z (Dub) Episode 122
Trunks provides Goku with a heart medicine from the future to ensure he survives the coming conflict. Technical Details (Funimation Dub) Trunks departs back to his timeline, leaving the