Truth

The stranger posing as Madara Uchiha keeps unspooling the story behind Itachi's massacre. A witness to countless wartime deaths by the age of four, Itachi grew into a devoted pacifist. Their father, Fugaku, secretly steered a plot for the Uchiha to seize control from the ruling Senju, and he slid Itachi into the Anbu to feed the clan intelligence. Itachi's true allegiance, however, lay with the village rather than his kin, a loyalty the Konoha Council and Danzo turned against the Uchiha by making him their informant instead. Once the Third Hokage's efforts at a peaceful settlement collapsed, the elders resolved to wipe the clan out. Itachi was left with an agonising choice: let the coup proceed and risk civil ruin, mass death, and an invasion that could ignite another world war, or destroy his own family to spare everyone that fate.

Madara recounts slipping into Konoha to avenge himself on the village and on the clan that had cast him aside, and how Itachi, the lone person aware he still lived, tracked him down and struck a bargain: aid in erasing the Uchiha in return for the village's safety. Itachi cut down his father, his mother, and his lover, yet could not bring himself to kill his little brother. Afterward the two parted, and Itachi reported his success before leaving Konoha, extracting from the Third a promise to keep Sasuke safe under threat of leaking village secrets. Sasuke rejects all of it, insisting his brother killed merely to test his own limits. Madara counters that Itachi's aims went further, from implanting Amaterasu within Sasuke to sealing away Orochimaru and the Cursed Seal of Heaven, and that his return to Konoha was meant to guard Sasuke from Danzo while he spied on the Akatsuki for the village.

Standing on a cliff as a hawk wheels overhead, Sasuke weeps over the brother he once adored and, transformed by the truth, rechristens his team from Hebi to Taka, declaring their new purpose the annihilation of Konohagakure and awakening his own Mangekyo Sharingan in the moment. Episode 141 of Naruto: Shippuden is part of the Fated Battle Between Brothers arc, adapting chapters 400 to 402, and aired 24 December 2009 in Japan and 9 October 2012 in English. The narrator claiming to be Madara is in fact Obito. The opening is Sign and the ending is It Was You.