Kashin Koji was revealed to be a clone of Jiraiya, created by Amado for the purpose of defeating Jigen and destroying Kara.
In the Boruto: Naruto Next Generations manga, the character Kashin Koji initially appears as a mysterious member of the Kara organization, an enigmatic group with its own agenda. His true identity and origins are shrouded in mystery, leading to much speculation among fans of the series. As the story progresses, it is revealed that Kashin Koji has a deep connection to the Hidden Leaf Village and bears a striking resemblance to the legendary Sannin, Jiraiya.
The revelation comes during a confrontation between Kashin Koji and Jigen, the leader of Kara and the vessel for the powerful Otsutsuki, Isshiki. During this battle, it is disclosed that Kashin Koji was genetically engineered by Amado, the head scientist of Kara, to be a clone of Jiraiya. Amado’s intention behind creating Koji was to have a powerful asset capable of taking down Jigen, as Koji possesses many of Jiraiya’s abilities, including the Rasengan and summoning toads from Mount Myoboku.
Kashin Koji’s fate after his battle with Jigen is left uncertain for a time. He manages to escape with severe injuries and is later shown to be recuperating, contemplating his next move. His ultimate goal remains aligned with taking down Kara and stopping their plans, but his current status and future actions are left open for further development in the series.