"Breakthrough" (突破口, Toppakō, Viz: An Opening) is chapter 642 of the original Naruto manga.
With the entire area set ablaze from the attack on Obito, Sasuke and Naruto watch, wondering if their attack was successful. Meanwhile, Tobiramateleports to Minato's side, noting that they had landed their attack before Obito could shield himself with the mysterious orbs. However, Obito emerges from the flames, unscathed as the orbs erase the black flames. As the two Hokage analyse the situation, Tobirama notes that Minato's arm should have regenerated by now, and comes to the conclusion that whatever Obito was doing involved the use of Yin–Yang rendering the regenerative abilities of the technique useless. As Naruto calls out to Sasuke noting they would have to lead the assault and attempts to go into Tailed Beast Mode. As a result, the mantle disappears altogether leading Tobirama to chide Naruto and Minato for not thinking. As Minato sheepishly apologises to the Second, they are all shocked when Gamakichi attacks Obito with the Starch Syrup Gun technique noting that the Summoning Technique was soon going to run out and he wanted to try something before he disappeared. As Obito deflects the attack under the shinobi's watchful eyes, Minato questions of his intentions lead Obito to decry the position of Hokage, leading Minato to blame the chain of events during the Nine-Tailed Demon Fox's Attack on his inability to recognise his own student. Naruto, however, tells the jinchūriki not to look down on the position because he was unable to acquire it, and — picking up on what was happening as Naruto formed a Rasengan — Tobirama teleports Naruto above Obito where he sends his attack crashing into Obito's back. Though Sasuke and Minato are shocked, Tobirama explains that it appeared that senjutsu was effective against Obito's form. As Minato notes that his son had become a sage like his own sensei, the silhouetted Yin half of Kurama notes that Naruto had grown up to be someone who loved his parents and had even persuaded his Yang-half to cooperate with him.