During the 3rd anniversary of the Japanese server of Dokkan Battle, there are 21 Dragon Balls to collect. Each day you can collect a Dragon Ball via various ways, with a hint provided how to obtain it. After collecting 7 Dragon Balls you can summon Porunga and he will grant 3 wishes.
The first set of 7 Dragon Balls
To get stronger, you need to train every day
Train a character
Investigate the button to switch from Events and Quest
Switch from Quest to Events 3 times
Fight together with one of the lowest level Frieza Minions
Go to the "Find Friend" screen ( Menu "bottom left small button on the home screen" -> Friends "most top option" -> Find Friend "second from the top option") and enter your own user id and press find, then try to add yourself as a friend