Board Thread:Versus Debates/@comment-3523655-20191213031023/@comment-32685487-20191213173917

In reality I don't think it was ever specified when Jiraiya actually learned Sage Mode. DB4 and the manga are the only real sources on it and I don't think they specified. So it is entirely possible Jiraiya learned his Sage Mode in the 3 years between P1 and P2, with the Akatsuki threat and Naruto's safety at hand more than ever it would make sense for him to finally decide to learn it for himself.