Koji Kashin's identity, revealed in Chapter 47 of Boruto: Naruto Next Generations, the ninja just needs to prepare for last part of his clash with Jigenor rather Isshiki Otsutsuki.
During the battle that took place in Boruto: Naruto Next Generations Chapter 48The Jiraiya clone was still using its skills to thwart Isshiki Otsutsuki. First he started with some fire techniques, then with hair using techniques. Of course you all fail because of the power and eye jutsu of Otsutsuki, but then this Jiraiya staged the hermit modethat we saw in Naruto's Manga vs. Pain in the Rain Village.
Contrary to that time Koji Kashin didn't have to concentrate for a few minutes to get the natural chakra. Furthermore, due to the imperfect control it always had, like the swollen nose, it does not appear to have had any signs of transformation. The technique is certainly active, however, as Mikio Ikemoto shows his eyes with the elongated pupils typical of toads in a cartoon.
Even Isshiki Otsutsuki acknowledges that the opponent is using historical technique: Amado has managed to modify the body of Jiraiya so that it can use the natural chakra better or not Supervision by the authors of Boruto: Naruto Next Generations? In the meantime, the clone managed to escape in extreme situations, even if it had several serious injuries. Therefore, it will be useful for the history of the manga in the future.