Awarded for summoning shenron.
You will need to acquire all seven dragon balls and wish at the dragon ball pedestal.
You can farm dragon balls in two ways:
1. Start new character, beat raditz, look for blue exclamation marks on map and beat time patroller for guaranteed dragon ball.
2. Grind the parallel quests 4, 23 or 79 and beat the time patrollers for a chance of dragon balls. It will say key item acquired if you have got a dragon ball.