Naruto's secret technique hidden from Lord Fukasaku
Naruto, the main character of the popular anime show Naruto Shippuden, has several arsenals. One of these is his massive amount of chakra given to him by the nine-tailed beast, the Demon Fox, and another would be the massive amount of healing power it gives him. In episode 156 of Naruto Shippuden. Sage Mode, an entirely new category of jutsu that appears to surpass ninjutsu, was found to further accelerate Naruto's healing ability. As shown in the episode, Naruto hears this fact and generates an idea in his mind, which he later practiced without Lord Fukasaku's knowledge. Although obvious details that…

Naruto's secret technique hidden from Lord Fukasaku
Naruto, the main character of the popular anime show Naruto Shippuden, has several arsenals. One of these is his massive amount of chakra given to him by the nine-tailed beast, the Demon Fox, and another would be the massive amount of healing power it gives him.
In episode 156 of Naruto Shippuden. Sage Mode, an entirely new category of jutsu that appears to surpass ninjutsu, was found to further accelerate Naruto's healing ability. As shown in the episode, Naruto hears this fact and generates an idea in his mind, which he later practiced without Lord Fukasaku's knowledge.
Although obvious details that would reveal the nature of the jutsu have been intentionally hidden, there are some clues that we could expand upon. The first is that it was a jutsu mentioned in previous episodes, given to Naruto by Itachi Uchiha, with the implication that it could be used to defeat Sasuke Uchiha. The second is that there was a gigantic cloud of smoke around Naruto after he was shown using it.
The first clue leads us to the fact that during Itachi and Sasuke's fight, one of the techniques that Sasuke Uchiha was unable to counter was Itachi's final move, Susanoo. That being said, it makes climatic sense that this particular technique is the one that Itachi Uchiha passed on to Naruto. The huge cloud of smoke dispersed around Naruto after the technique was associated with the massive size of the creature summoned when Susanoo is performed.
There could be many theories and speculations, but I assumed that this is the answer to this mystery without depending on the manga. It is eventually revealed as the story progresses. However, it seems that Naruto would be looking to synergize his three most powerful arsenals somewhat; the Demon Fox Chakra, Sage Mode and Sosanoo. I'm sure it will be an amazing revelation when it finally gets animated.