It's been 2 years after Trunks killed the Androids and Cell. Now the world has been in peace and starting to rebuild itself. However Trunks kept training in case another threat would show up and mistakenly he thought that today was that day. He saw a Saiyan Pod crashing down near west city and he thought this was a attack so he flew towards where it crashed and landed down.

Trunks Briefs: "HEY! I will give you a warning. Leave now or die. I won't have another thing destroy the world that Gohan died to protect. I will carry his wish for peace. What will it be."