Sasuke's Answer (サスケの答え, Sasuke no Kotae) is chapter 627 of the Naruto manga.
With Hashirama finishing his story, Sasuke iterated how ironic it was that his brother Itachi, who was from the Uchiha clan, and had never heard Hashirama's story directly from the source, was the one who had inherited his will so strongly. However Tobirama notes that there had been several Uchiha throughout history which had transcended the limitations of their clan and put the village first. One such person who stood out in his mind was Kagami Uchiha. Noting that he did not hate the Uchiha, but in his capacity as Second Hokage, had to find a way to mediate between clans and the village's well-being — the former being something he noted his brother foolishly thought would dissipate with the creation of the village system. In turn, both the Third and Fourth, noted that they had fallen short of their predecessor, and the expectations people had of them respectively. Having heard all he needed from the Hokage, Sasuke comes to the conclusion that the village and people that Itachi sacrificed his life to protect should not be wasted, and decides to enter the battlefield in order to follow his brother's will, with Orochimaru following out of interest. Motioning to Tobirama to prepare to transport them, Tobirama informs his brother that they could not do so because they were bound. As they left the Naka Shrine, Suigetsu who decided that fighting alongside who he deemed the four strongest reincarnated shinobi and three monsters was not a viable option tried to slip away, only to be met by a kick from Karin. She yells that she will never forgive him for what he did and Sasuke immediately apologises. Karin, who visibly cannot contain herself, runs up to Orochimaru and tells him that he stabbed her. He recommends that she should cooperate Sasuke for the time being so she reluctantly rubs against Sasuke, saying she has no other choice. As the Hokage prepare to make their way to the main battlefield, Hashirama — who can barely contain his excitement at this point upon seeing the village again — directs his fellow Hokage to their respective faces on the Hokage Monument before declaring that he wanted to know what his old friend had been up to, Tobirama declares that this time he would stop Madara for good, Hiruzen notes that he had not been to war in so long but vows to give his all this time, and Minato, delighted that he will finally meet his son, promises to make up for not being there with a huge surprise.