The Fourth Hokage's Death Match

Synopsis
Kushina successfully gives birth to Naruto, and Biwako takes the baby away, only for her and fellow midwife Taji to be killed by Tobi, the masked man. Tobi places explosive tags on the newborn Naruto and tosses him into the air, forcing Minato to catch him, remove the tags and use his Flying Thunder God Technique to teleport outside. Tobi uses the opportunity to use Kamui to teleport himself and Kushina elsewhere, where he extracts the Nine-Tails out of her and, controlling it with his Sharingan, decides to attack Konoha. Meanwhile, Minato teleports to one of his safehouses to keep his newborn son safe and manages to teleport back to Kushina, who had the Flying Thunder God seal marked on her Eight Trigrams Sealing Style, and saves her from being killed by the tailed beast. He brings her back to the safehouse, placing her next to Naruto and dresses in his Hokage attire.

In the village, Guy is pestering Kakashi to compete in another challenge while Tobi sneaks into the village. He summons the Nine-Tails right inside the village and allows it to wreak havoc. Sensing the tailed beast, the Third Hokage prepares to go into battle; Chōza, Shikaku, and Inoichi prepare to defend their village as well. Minato teleports to the village to defend it, and the fox fires a Tailed Beast Ball towards him. Using his Flying Thunder God: Guiding Thunder technique, Minato warps the Tailed Beast Ball to a safe distance away. He is immediately engaged in combat with Tobi, who attempts to use Kamui to send Minato elsewhere; however, Minato teleports to a safe location just in time. Tobi follows Minato there and praises his Flying Thunder God techniques, while Minato, realising that the masked man in front of him possesses a Sharingan strong enough to control the Nine-Tails while infiltrating the village undetected, suspects Tobi to be none other than Madara Uchiha, albeit immediately dismissing the thought since Madara was thought to be long dead.

Minato begins his assault on Tobi, who produces chains from his wrists, but is unable to land a successful hit due to Tobi's intangibility. Noting that Tobi would have to manifest physically in order to strike back, Minato throws one of his Flying Thunder God Kunai at Tobi's head while rushing towards him at the same time. Right as the kunai goes through Tobi's head, he materialises in order to grab a hold of Minato; however, Minato forms his Rasengan and teleports to the kunai's location behind Tobi, and manages to land a successful hit, marking him as well. Tobi is wounded from the attack, as his left arm begins to peel and fall off. Having branded Tobi, Minato is able to teleport to him right away and places a Contract Seal on him, wresting the Nine-Tails from his control.

Trivia

 * Team Tobirama as well as Torifu Akimichi were not present during the episode, in contrast with chapter 503.
 * In the manga, Minato glared at the Nine-Tails and Tobi, the masked man, after telling Kushina that Naruto was safe. In this episode, it happened when Kushina told him that Tobi's objective was to destroy Konoha.
 * Minato notices Tobi's Sharingan as the latter uses Kamui; however, it is a normal Sharingan eye and not the Mangekyō Sharingan. This goof also persists in the previous episodes up until the point where Tobi's true identity is revealed, at which point his Mangekyō Sharingan is shown whenever he uses Kamui.
 * After Tobi is struck with the Rasengan, his left arm peels off. This is apparently an error, as Tobi's left arm was his original and natural arm, while his right arm was the artificial arm.
 * Since Boruto can use Flying Thunder God Technique to transport himself to another dimension, it is likely that even if Minato had gotten trapped by Obito in the Kamui's Dimension, he would have still been able to get out.

Credits
Bitwa Czwartego na śmierć i życie!! (odcinek) Le Dernier Combat du quatrième du nom !