I ran a one-off adventure (2 other players, finished in about an afternoon) where I gave the players about 1.5 times as much XP as Keiko had at that point (so they were solid Chunin) and told them "give me your character concept, I'll make you a character and you'll have a week to read the rules and edit him". Ask me for ideas on Jutsu or combat styles, and I'll make rules for them. The PCs decided not to bother with too much back-and-forth creating jutsu (which I was thankful for, seeing as I'm not sure how to balance them) so we had a weapons user and a Stealth/social character.
The setting was basically the canon narutoverse, but on the first stages of descent into a final "Tippyverse" state (I've spent some time thinking about this, you see - I might make a short fic or a quest about it at some point, when I have more free time in meatspace) as several nations finally hit their tipping point and started becoming much more powerful than the others. They were tasked with a scouting mission that went south, and then had to somehow return home while in territory just being invaded/occupied by Sound (and as an objective of opportunity, had to try to find the secret of Sound's power and bring it back to their superiors if they could). It went well enough all things considered.
DISCLAIMER: I made a homemade system for range, mobility and injuries. I don't understand how to use the formula for dice in practice, so I ignored it. I made a bunch of minor bloodlines too for them to choose from, if you're interested.
FEEDBACK: I loved the XP system (even if it was mostly only used at chargen - and chargen was long, but fun for me who likes making characters with my players), the mass combat system, and the rules for clones and replacement.
@eaglejarl: I guess I could try that, yes. IRL time constraints means that it won't be before next week at least though. I'll get back to you on that if I can do it. No promises, but hope