By now the arch of the Otsutsuki is continuing at full speed in Boruto: Naruto Next Generations entering more and more in the culminating phases. The secrets about this alien clan are revealed chapter after chapter thanks to the appearance of Amado, the scientist who helped Kara until recently.
The evolution of the situation in Boruto: Naruto Next Generations it allowed Naruto, Sasuke, Shikamaru and the others to obtain fundamental information from Amado. We have been getting revelations for a few chapters about the power of the Otsutsuki, their origin and how to defeat them. In the latter situation, Koji Kashin, the mysterious masked ninja who is now facing Jigen, will come in handy.
In Boruto: Naruto Next Generations 47 continues the battle between Koji Kashin and Jigen, with the latter unable to use all his power due to the limit of his body and the much chakra used against Naruto and Sasuke. Amado knew this and was waiting for this moment since, as he explains, the way to avoid a reincarnation in Kawaki is that Isshin reincarnated first in Jigen.
In fact, Kawaki's karma suddenly activates and then completely leaves his body, coming from Isshin who reincarnates definitively with Jigen's body. This time it's a different figure that Koji Kashin has in front of him, a figure full of power that begins to destroy and shrink various objects, including the frog that provided the video to Naruto and his companions.
At the end, Boruto: Naruto Next Generations finally reveals the identity of Koji Kashin who is none other than a Jiraiya clone, confirming one of the many fan theories. Sannin will likely be a victim of this process, but this has provided Naruto and the other ninja in the Leaf Village with chance to kill Isshin Otsutsuki.