Decryption

Poring over the cipher his teacher left, Naruto spots that the mark everyone took for a "9" is really the katakana "ta" rendered in Jiraiya's odd hand, a detail only he could catch from having read the man's stories. The Cryptanalysis Team decides the note was addressed to Naruto and that its other digits mark page numbers in the Icha Icha books. Much to Kakashi's chagrin, he must read passages from the racy volumes aloud until the buried message surfaces: the genuine one is not among them.

Passed along to Fukasaku, the cracked message ties back to Jiraiya's earlier observation that none of Pain's Six Paths resembled Nagato. Fukasaku wins Tsunade's leave to take Naruto to Mount Myōboku for Sage Mode training, and Naruto, burning to avenge Jiraiya, agrees and is reverse summoned there by Gamakichi. Reflecting on the Great Toad Sage's prophecy, which foresaw both Jiraiya's novels and their hand in cracking the cipher, Tsunade resolves to place her faith in the toad's foretelling, accepting Naruto as the prophesied child.

At Mount Myōboku, Fukasaku lays out the groundwork of senjutsu with Gamakichi paraphrasing for the young ninja, then drops the grim catch: to take in natural energy, Naruto must first perish. Naruto learns Gamakichi summoned him because toads can call on humans bound to them by blood contract. Drawing on chapters 407 through 409, the episode falls in Pain's Assault arc and carries the opening A World That Was Transparent alongside the ending Bicycle.