"The End of Tears" (涙雨の結末, Namida Ame no Ketsumatsu) is episode 134 of the original Naruto anime.
Sasuke, having activated his Cursed Seal of Heaven level 2, laughs and arrogantly tells Naruto he has a feeling he will not lose. Enraged, Naruto charges at Sasuke, and the two clash sending up a cloud of debris. When the dust settles, Naruto is shocked to see a giant wing coming out of Sasuke's back, which has deflected his attack. Sasuke extends the wing and sends Naruto shooting towards the opposite side of the river.
A second wing tears through the back of Sasuke's shirt, and he groans in pain. He remembers Sakon's warning not to use the fully released Cursed Seal for too long. Knowing that his body will erode if kept in this state, Sasuke tells himself he hasn't any time to waste. Naruto stands, his left hand completely immobile. He realises the Nine-Tailed Fox form is taking a toll on his body, which Sasuke happily notices as well.
Sasuke tells Naruto that they are fighting in the Valley of the End and that it is the perfect stage for their battle. A series of flashbacks recap the two boys' relationship up to this point: the formation of Team 7; Sasuke's superior abilities; Naruto's incredible improvement; Sasuke's subsequent jealousy; and their inevitable rooftop fight.
Sasuke envisions Itachi's distorted Sharingan, which drives him to form Chidori a third time. Naruto straightens up and forms a Demon Fox Rasengan using only his right hand as his left hand is still out of commission. The strength of Sasuke's Chidori increases, becoming a Flapping Chidori. Both ninja charge at each other with their ultimate techniques. They collide in an explosion of blue and red chakra that forms a swirling black sphere of energy. At the last moment, Sasuke chooses to punch Naruto in the chest rather than impale him with the Chidori. Likewise, Naruto only scratches Sasuke's forehead protector, disproving the boy's earlier taunt and minimising the effects of the Rasengan. Getting closer, Kakashi senses the massive chakra and tells Pakkun to hurry.
Naruto and Sasuke are left hovering within the sphere, gazing sadly at each other. A vision of a younger Sasuke and Naruto shows the two form a seal as a symbol of friendship, and they smile at each other. The bright light then slowly dissipates and as it fades away, Naruto is shown lying on the ground, unconscious with Sasuke standing above him, revealing that Sasuke has emerged as the victor in their fight. Sun light breaks through the clouds, illuminating the two boys, and focuses to a point on Naruto's face before it disappears altogether. Sasuke stares down at Naruto while Sasuke's own scratched forehead protector loosens and falls to the ground, presumably confirming that Sasuke has severed ties with Konoha. It begins to rain. Sasuke is wracked by a sharp pain in his arm and falls to his hands and knees looking Naruto straight in the face.
A while later, Kakashi arrives at the scene, but Sasuke is nowhere to be found. Kakashi slowly picks up the fallen Naruto, apologises for not making it in time, and acknowledges what must have been Naruto's desperate effort to save his friend. Sasuke walks through the forest assailed by memories of his parents and brother. He again recalls Itachi's last words to him, that to unlock his Mangekyō Sharingan he must kill his closest friend. Back at the waterfall, Pakkun and Kakashi discuss the irony of Naruto and Sasuke fighting at the Valley of the End and the never-ending battles of the ninja world which like the river will go on forever. Naruto slowly opens his eyes, revealing Sasuke's choice to leave without killing him. Returning to Sasuke in the forest, the boy asserts that he will not do as his brother bids, and that he will obtain power in his own way. Sasuke then walks into the darkness.