I think it would be okay for Kakashi to give your character some tips as for concealing their identity as an ANBU.  Like nonchalantly on a mission or in the ANBU HQ or something. I would refrain from having him be her full-on mentor though.  Kakashi doesn’t really have a history of being willing to teach others.  (remember when he failed all those Genin before Team 7).

I say do a variation! People look somewhat different even in a clan.  You can keep the same color schemes to keep a resemblance if you want!

I think that would be fine, just make sure to specify that it’s a guilty pleasure oc, so we can focus on critique of other things about them instead of what makes them a guilty pleasure oc.

I think it would absolutely be alright. It’s such a great idea and has been used in other anime like Attack on Titan. It’s a viable means of long-distance communication, so I see nothing wrong with it. 

Mostly from what I’ve observed, there’s a fairly even mix of all of these. Kabuto for example was a spy in Konoha, but also helped him destroy the village. Karin and Juugo were test subjects. The sound four were originally test subjects before becoming his elite bodyguards. Aside from that, any member of Otogakure were part of Orochimarus crew. 

Not dumb at all! And apologies for this taking so long to reply to. 

We do know that some of the kids started pretty early, particularly in Kakashi’s generation. We know that a lot of kids (in the Japanese system) start school as young as 6. 

We can infer from some graduation timelines for various chracters (Itachi, Kakashi, etc.) that some kids are pretty much fast-tracked through the system, resulting in pretty young child soldiers. 

Basically, what might take some kids six years might take others three or four depending on if they’re ‘geniuses’ or not, or if they have high-level help or are pushed to succeed at home. 

I hope this makes a bit of sense and helps!

I actually think 12 is a perfectly reasonable age within canon, especially if this is not set during wartime. 

In wartime, they’d be trying to churn out as many soldiers as possible, but during times of peace, there would be less stress put on the school system. 

So i think you could even go as young as 10 or 11 if you were really pushing it. I just can’t imagine having that lever of responsibility as a 10 or 11 year old. 

I think short answer, it’s a no. 

I can see how someone might do it right if they’re very careful about writing it, but it falls in too closely with the jinchurriki. And above that, it’s not terribly feasible within the culture, though to my ‘western’ ears, demon might be too polarizing of a word.