Board Thread:Fourth Databook/@comment-4271790-20141104211032/@comment-4271790-20141105004233

FF-Suzaku wrote: To me, the book seems to make it pretty clear that "Yin-Yang Release" and "Yin Release and Yang Release" aren't the same thing.

I think what we can discern from this is that being able to use Yin-Yang Release doesn't necessarily mean an individual has mastery of both Yin Release and Yang Release. I agree. So technically, Hashirama has Yin being able to use the Bringer of Darkness Genjutsu (from the manga), but wasn't listed has having Yin in the databook, but only Yang. Tobirama can use the BoD genjutsu (from the anime), and was listed to have Yin and Yang. So maybe Tobirama can use Yin, Yang, and Yin-Yang; and Hashirama maybe can use Yin and Yang, but not Yin-Yang? That is my best guess, even though you said that usage of Yin and Yang does not confirm usage of Yin-Yang.