The mystery of whether Black Goku and Zamasu are one and the same has been answered. But the question remains as to how these two villains are connected.

Ever since Black Goku appeared on Earth, his familiar ki had puzzled Beerus and Whis. The two gods even traveled to Universe 10 to check on its Kai, Gowasu, and his apprentice, Zamasu. While the green-skinned trainee's ki is indeed similar to Black's, they concluded it didn't feel as evil.

In episode 56, Zamasu's sudden appearance while Black and Goku were fighting proved that the two were two different individuals. But Zamasu's command to Black and his reminder that he would be the one to finish the Saiyan raised questions as to the relationship between the two.

The upcoming episode, titled "Advent of the Immortal God Zamasu," hints that Zamasu's backstory might be revealed. Perhaps viewers will finally have an inkling as to why he appears hostile to humans.

The trailer for episode 57 shows Goku and Black still going at it; only this time around, Goku is powered up to Super Saiyan Blue. Meanwhile, Future Trunks faces off against Zamasu. The kai-in-training looks unusually calm and is even smiling triumphantly at one point, leaving viewers to wonder what tricks he has up his sleeve. The clip ends with Goku preparing to unleash a Kamehameha attack.

A translation for the Japanese-voiced trailer begins with Goku's amazement that "We have to fight Zamasu, who's in cahoots with Black?" He also reminds Trunks that they "better brace ourselves or this could get ugly." While he exhorts the youger Saiyan onward, he also mentions that their attacks don't have any effect on Zamasu.

There have been reports that Black and Zamasu might fuse into one being and that Goku and Vegeta would also do the same. While there are those who are waiting for Gogeta to return, it's unlikely to happen as the two Saiyans have said they will never fuse again.

"Dragon Ball Super" episode 57 is set to be aired on Fuji TV on Sept. 4 at 9 a.m.