"Dragon Ball Super" Episode 61 revealed the story of how Black Goku gained his powers while he was fighting with Son Goku. Black Goku also unveiled the reason why they exist on "DBS" and it is apparently because of Trunks.
Black Goku revealed that he is the real Zamasu which came from a different timeline on "Dragon Ball Super." He exchanged his body with the real Son Goku so he could use Son Goku's powers to defeat Kaioshin Gowasu in Universe 10 to steal the green Potara earrings as well as the Time Ring. "Dragon Ball Super" saw Black Goku succeeded in his plan and killed Gowasu and now owns the Time Ring.
As for Future Zamasu, it was revealed that Black Goku traveled to Future Trunk's timeline using the Time Ring and searched for Zamasu to help him fulfill his Zero Mortal Plan which is to kill all mortals. Future Zamasu killed Gowasu again to steal his Time Ring on "Dragon Ball Super." Unfortunately, the Zero Mortal Plan plan worked well as Black Goku and Future Zamasu were able to kill all the Gods of Universe 10, SportsRageous reported.
Black Goku's revelations continued on "Dragon Ball Super" while fighting with Son Goku and he revealed that he killed Goku, Chi Chi and Gohan in another timeline, Attack of the Fanboy reported. This made Son Goku angry but he was still not able to defeat Black Goku. Now, it's Trunks and Vegeta's turn to fight the enemies but Zamasu taunted Trunks by telling him it was his fault that they exist on "DBS."
The "Dragon Ball Super" enemies explained that Trunks traveled in time to save Son Goku from dying due to a heart virus. Because of his multiple time travels, another Time Ring was created which caused Black Goku and Future Zamasu to own the Time Rings. If Trunks let Son Goku die in the past then there should be no Black Goku today and no Time Rings have been created on "Dragon Ball Super."
"DBS" then saw Trunks becoming angrier this time which seems to be comparable to Super Saiyan Blue. Will Trunks be able to defeat Black Goku and Future Zamasu on the next episode of "Dragon Ball Super?" Will his power be enough to kill them or is it him who will be killed by the enemies on "DBS?"
Watch Trunks' new form on "Dragon Ball Super" below.