Uncover Black's Identity! Off to the 10th Universe's World of the Kai's!

Goku, Beerus, and Whis travel through space to the Sacred World of the Kai in Universe 10. During the journey, Whis reveals his suspicion: he believes Goku Black may be connected to Zamasu, a Kai who serves as apprentice to Gowasu, the Supreme Kai of Universe 10. Whis describes Zamasu as a fighting genius, an unusual distinction among the typically non-combative Kais. Goku grows excited at the prospect of fighting a divine warrior, which irritates Beerus to the point of threatening to push him off their transport.

Upon arrival, they interrupt a conversation between Zamasu and Gowasu about the purpose of mortals. Zamasu has been arguing that humanity should be destroyed, and Gowasu counters that Kais exist to observe and nurture creation, never to interfere. Zamasu's reaction to Goku, a mortal standing on sacred ground, is immediate hostility. He nearly attacks before Gowasu restrains him and apologizes. Whis brings Gowasu up to speed on Goku Black, the Time Rings, and the resemblance to Goku. Gowasu leads them to the temple where the Time Rings are kept, and all are accounted for.

Gowasu instructs Zamasu to spar with Goku as part of his training. Beerus warns that holding back will cost Zamasu his life. Goku transforms into Super Saiyan 2, shocking both Kais, and the fight begins. Zamasu is skilled, catching Goku's punch and countering with precise strikes, but as Goku pushes harder, the gap becomes clear. Goku ends the match with a clean punch and compliments Zamasu's strength. Zamasu nearly retaliates in anger before Gowasu stops him. Beerus, having seen enough, prepares to leave.

Zamasu's introduction is meticulously crafted to create unease. He pours tea for his master with perfect composure while discussing the extermination of an entire species. His fighting skill is real, good enough to catch Goku's opening punch and counter effectively, but it is his ideology that makes him dangerous. Where previous Dragon Ball villains wanted power or dominion, Zamasu believes he is righteous. He sees mortals as a stain on creation, and his apprenticeship under a Supreme Kai gives him access to knowledge and artifacts that could make his beliefs catastrophically actionable.

On Earth, Future Trunks' encounter with Android 18 provides a brief but effective character moment. She jokes about wanting reimbursement for him killing her future counterpart, then immediately drops the act to rejoin her family. It is a small scene that shows how thoroughly the present timeline has healed from the wounds that still define Future Trunks' world.

On the return trip, Whis states plainly that Zamasu was suppressing a cold heart and that the evidence points toward him being connected to Goku Black. Beerus regrets not destroying him on the spot, while Goku naively insists Zamasu did not seem like a bad person, prompting Beerus to call him dangerously trusting. The confirmation that Zamasu's ki matches Black's narrows the mystery significantly, but the how remains unanswered. Zamasu genuinely did not seem to know about the Time Rings, and Gowasu appeared oblivious to any wrongdoing. The final shot of Zamasu pouring tea while promising he will never forget Goku is chilling in its restraint. Something has been set in motion that polite conversation and sparring matches will not be able to stop.