Sasuke's Answer (サスケの答え, Sasuke no Kotae) is episode 370 of the Naruto: Shippūden anime.
After Madara's Susanoo-clad Kurama was shattered by a thousand punches, he and Hashirama managed to face each other directly. As Hashirama fell, Madara noted that unlike all the other times, he was the one left standing. As Hashirama tried to speak reason to his former comrade and Madara constantly ridiculed the dream they once shared, Hashirama pierces Madara from behind with a sword revealing that it was only a wood clone that fell and not Hashirama himself. Declaring that he would protect his village believing it to be the best way to protect shinobi, and that anyone that tried to destroy that would receive no forgiveness from him. As Madara fell, Hashirama resolved himself to endure in order to protect his dream while Madara, still resolute, declared that he would one day become darkness which enveloped the village. Back in present day, Hashirama tells those present on site that he did not know how Madara survived, because he was sure he had killed him. He then goes on to tell them that it was for the sake of the village. After explaining what his vision for the village was, Hashirama goes on to explain that shinobi were people who endure to achieve their goals, but depending on what they chose as their goals, it could change who they were; like the way Madara, and he himself had changed. With the First Hokage 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. Minato expressed excitement in finally being able to meet his son as well as bringing him a present to make up for not being able to be there for him as a father, as Hiruzen notes that he had not been to war in so long but vows to give his all this time, Tobirama declares that this time he would stop Madara for good and Hashirama noted that he couldn't help but be curious as to what his long-time friend had been up to.
Sasuke's flashback to when Itachi told him he was weak because he lacked enough hatred aligned more with the manga, in which Itachi told Sasuke this after he cast Tsukuyomi on Sasuke and Jiraiya casting the Summoning: Toad Mouth Bind. In Naruto episode 85, Itachi told Sasuke this before either technique was cast.
There was a meteorological inaccuracy at the conclusion of Hashirama and Madara's battle. The sky was shown to be clear with some clouds floating around but it was raining. When raining, clouds cover the entire sky. This inaccuracy was not present in the manga.