Board Thread:Naruto Discussions/@comment-28939725-20161116235549/@comment-4912646-20161118235714

Sasori's chakra threads are also blue on volume 55's cover, so at least that's consistent. There's also the fact that Kisame mistook Guy's blue/green aura of sweat as chakra, which suggests it may be a common colour. Even though we know people have chakra with different colours (at least when viewed by dōjutsu), it seems highly unlikely Kishimoto ever really put any thought into what each person's chakra looked like (otherwise he could have just had Ao mention Shisui's colour, for instance).

It's just that he used to be pretty consistent about drawing Naruto's chakra and techniques yellow (or red/orange with Nine-Tails influence) up until the last couple of years. Curious if anybody has access to any of the earlier artbooks, since they may be the first place that Rasengan was coloured. The newest one obviously contains a mix of blue and yellow, since it covers from before volume 52 up until the end.