One of the most intriguing developments of Boruto: Naruto Next Generations has been the mysterious power of the Karma mark that suddenly appeared on Boruto after the battle with Momoshiki Otsutsuki. The latest arc of the manga has seen him and the rest of the Uzumaki family grow closer with the mysterious Kawaki as the two of them have been trying to learn more about its power, but the latest chapter of the series teases that learning more about this power will only lead to ruin as there's a much more sinister purpose for it.
Chapter 38 of the series sees Naruto and Sasuke take a heavy loss from Jigen as he unleashes the full power of his own Karma mark. But after it was surprisingly revealed that Jigen is actually the host for a new Otsutsuki Clan member, it seems that the Karma mark is actually another way to bring the Otsutsuki Clan into the world.
Not only did Jigen's full use of the Karma power make him sprout a horn like the Otsutsuki Clan members, but it gave him an inhuman increase in power that helped him to easily take down Naruto and Sasuke. This power pushed Jigen passed its limit, and the Otsutsuki Clan member within him had lamented the fact that Jigen is losing his usefulness as a host.
This is where the true purpose of Karma is teased even further as Jigen asks Naruto how Boruto is coming along. He notes that his Karma is developing well, and like Kawaki, it seems that Boruto just might be used as a host for the Otsutsuki power as well. This was teased in an earlier chapter which saw Jigen forcibly activate the Karma power of both Boruto and Kawaki, and even transported himself through it, and could hint that these two are in far more danger than expected.
While Boruto and Kawaki have both been boosted in power thanks to the Karma mark, it seems that Kawaki has already progressed to the point where his full activation of it already leads to him sprouting a horn like Jigen. If Boruto's getting strong at the same rate, he could very well be growing his own sudden horn too.
Originally created by Masashi Kishimoto for Shueisha's Weekly Shonen Jump in 1999, Naruto follows a young ninja, with a sealed demon within him, that wishes to become the leader of his home village. The series ran for 700 chapters overall, and was adapted into an anime series by Studio Pierrot and Aniplex that ran from 2002 to 2017. The series was popular enough to warrant a sequel, Boruto: Naruto Next Generations which is set several years after the events of the original Naruto story and features the children of many of its key characters such as Naruto and Hinata.