History's Mysteries
Goku meets Goku Jr.
After a spar, Goku Jr. and Vegeta Jr. stumble upon a collection of antique capsules that all bear Bulma's name. Interested, they begin rummaging through them and find numerous things, including Trunks repaired Time Machine. After figuring out how to operate it, Vegeta and Goku decide to journey back in time to finally solve the mystery surrounding what actually happened at the Cell Games.
While in the past, they receive training from their ancestors and participate in the Cell Games themselves, just for fun.