Board Thread:Fourth Databook/@comment-4366149-20141122004623/@comment-4912646-20141124050135

Regardless of whether Jūgo's techniques are kekkei genkai, they should still be classified as senjutsu, since they are an application of his "Sage Transformation" ability. That said, this book may still hold more answers about senjutsu and Sage Transformation, if the the White Snake Sage's entry is anything to go by.

As for Truth-Seeking Balls, they were said to be made of "Six Paths Sage Chakra" in chapter 674, and their entry in this very book says they are used by Six Paths Senjutsu users.