Complete Then Repeat
Complete the quest if you see Key Item pop up. Once you’re done, you’ll see a shiny Dragon Ball as one of your rewards, bringing you ever closer to making a wish in Dragon Ball Xenoverse 2. Now all you have to do is repeat the process six more times until you have all seven.
Unfortunately, you can’t just choose to go through the quest again from some mission end screen. You have to wait until you’re loaded back into Conton City, which can take quite a bit of time. Accounting for load times, and assuming you’re skilled enough to beat the entire quest quickly, each successful run should take about 6-8 minutes total. If a run is a failure, you shouldn’t find yourself in the quest for more than three minutes, and retrying from within the mission is a lot faster than exiting and choosing it all over.
As long as you don’t give up after a few failures, you should be fine and well on your way to having a full collection of these valuable Dragon Ball Xenoverse 2 items.