The latest arc of Boruto: Naruto Next Generations has taken us into the Hidden Stone, where there is a major plot unfolding. Lord Onoki has been revealed as the mastermind behind Lord Ku and the Akuta monsters, which has left Boruto and friends scrambling to find Mitsuki, and get back to Hidden Leaf with warning. Unfortunately, Boruto, Sarada, and Shikadai have all gotten seperated, with Boruto in precarious position of having to keep company with Onoki.
As you can see in the synospsis for the next chapter of Boruto (via Reddit), the young ninja is going to need to locate some kind of special artifact, in order to get out of Hidden Stone at all:
"Boruto EP #84 (12/2 Broadcast)
“Oonoki’s Thoughts, Kuu’s Thoughts”
Find the ‘Heart of Stone’ !!
Each and every one of his comrades who get separated from one another will head over to Inojin’s location…!
Boruto has gotten trapped by the training ground’s barrier!!
After being on the receiving-end of Kuu’s attack, Boruto and his comrades have gotten separated from one another. Even though each of them are heading towards Inojin’s rendezvous point, Boruto gets completely lost in Iwagakure’s shinobi training grounds, which has a formed barrier. In order to escape, he needs a ‘Heart of Stone’. However, it’s something that can only be found once-in-a-lifetime!?
Will they be able to get Mitsuki back!?"
There is no confirmation yet about what this "Heart of Stone" actually is, or what it does but the clues may be found in the history of Naruto: Shippuden. Episode 332 of that series is called "A Will of Stone", and it featured a major moment from none other than Onoki. During the intense battle between the Kage and Madara Uchiha, Onoki is knocked unconscious by one of Madara's attacks. Onoki's mind calls back to his conversations with the First Tsuchikage, about the Iwagakure shinobi and their "Will of Stone". That notion inspires Onoki to break through his weakness with a powerful Dust Release attack, saving the Kage.
Given where Boruto's current "Mitsuki Arc" is, it's not hard to see this next episode slowing things down, so that Boruto (and subsequently the fanbase) can learn what exactly made a hero like Onoki take such a drastic turn into villainy. The "Heart of Stone" may not be just a physical artifact, but rather a mindstate That Onoki tries to teach Boruto is a necessity of this harsh and savage world.
Catch Boruto streaming weekly on Crunchroll and Hulu - and the English Dub Saturdays on Toonami.