Naruto is generous to fanfic: the canon itself left hundreds of open gaps. What happened to Kushina before the Nine-Tails? How did Sasuke grow up between the genin exam and the chunin arc? Did Itachi really stand outside the village alone? AI co-authoring is a fast way in — you describe the setup, get a chapter, polish the details.
Name the fandom ("Naruto"), the era you want (pre-canon, Shippuden, Boruto, AU), your POV character, and one plot hook. The AI writes a chapter with the signature pacing of a ninja scenario: a short scene-setting beat, a conflict by paragraph 2-3, a twist at the close. In natural English, naturally, without that machine feel. Stop, rewrite, keep going — until your saga lands. The text stays yours; we don't publish anything without your "Share."