I liked the read but I don't understand how a six year old had been in the ANBU for ages. And please know this isn't destructive criticism, I'm just curious about that plot point. Also, I'm not entirely sure that Hidden Cloud has ANBU. I think it might be best if you took the ANBU stuff out, and made your character a Genin. But a prodigy Genin.

Everything was well written and I would love to read more.

You could use the deaths of your comrades to push your character down a darker road to join some sort of ANBU. It could be a driving point that ultimately turns you into a cold blooded assassin. I could be wrong about Cloud not having ANBU, some sources say that every village has them while others limit it to Leaf, Sand and Mist.

I did some reading on the matter and it seems the lack of information about it could help validate it's existence. Kishimoto released a databook a while back that explained Hunter-nin were Mist exclusive among a lot of other things, and if ANBU were exlcusive to only Leaf, Mist and Sand it should have been denoted there.

But perhaps you could skip this all together. The Raikage bestows Kanji Tattoo's to people of prominence so perhaps you could use that to give you the same prestige as an ANBU. Maybe it could be "Lighting" on his right arm and "Blade" on his left or something. Given the lack of information you could go either way, but bear in mind Kakashi was considered an elite genius and he wasn't even an ANBU until he was 13..but the guy was a Chunin at 6 which imo seems pretty excessive.

I can't wait to read more though, so please get to work! :D