What is Left Behind (遺されたもの, Nokosareta Mono) is chapter 405 of the Naruto manga.
Fukasaku explains that Jiraiya gave him a coded message about Pain before dying. Naruto instead focuses on Tsunade, blaming her for letting Jiraiya go on such a dangerous mission by himself. Tsunade makes no effort to refute his claim so he storms out. Naruto runs into Iruka, who offers to take him to Ramen Ichiraku, but Naruto declines. Iruka tracks him down later and comforts him about Jiraiya's death, saying how proud Jiraiya had always been of Naruto and how, as Jiraiya's student, he lives on in Naruto. Meanwhile, Tsunade tasks Shikamaru with deciphering Jiraiya's message before taking some time alone to cry for Jiraiya.