Board Thread:Naruto Discussions/@comment-25645405-20141128183407/@comment-4271790-20141202001250

NoJutsu wrote: The problem is still that Black Lightning techniques are tagged as Lightning Release in canon, unlike black flame techniques that still get tagged as Blaze Release. Also it was stated by Kakashi that the only way to produce an advance nature that's made up of two natures is via a kekkei genkai. So since Blaze Release was not one of the five basic Releases and was also a kekkei genkai, it was very easy to argue that it is an advanced nature. Honestly, Kishi probably couldn't make up his mind on what to make of the black flames. Maybe it was, but not now. An advanced nature is a nature made up of two or more basic nature transformations. While others like Wood and Ice were stated to have two basic natures, Blaze wasn't. It was an assumption. We assumed Blaze was advanced, but the fact of the matter is that Blaze is not made up of two natures, it is just a variant of Fire Release.

Edit: Blaze Release techniques such as Amaterasu and Blaze Release: Kagutsuchi were tagged as Fire Release in the databooks.