Board Thread:Theories and Speculation/@comment-1512913-20161119171442/@comment-4912646-20161128225840

Mū is probably the single greatest example of how unreliable the latest databook can be as evidence of anything, since it's an instance where the manga isn't even relevant and the book is just contradicting itself. Mū is given four out of five natures, singling out Water as the only one he can't use. Then his technique's description goes on and on about water particles, despite the manga providing no indication that water is involved. So no matter what we're forced to speculate, either that the nature chart was wrong or that water can be manipulated without Water Release.

It would be one thing if this was the only error like this, but the databook is full of them. As mentioned earlier in the thread, we have Hashirama and Nagato's lack of Yin Release possibly implying that not all genjutsu are Yin, and multiple characters who used Yin—Yang Release lacking one or the other, which may mean it can be used without knowing both somehow. This has also led to natures being removed from pages like Genjutsu Protect and Izanagi.