Board Thread:Theories and Speculation/@comment-24267641-20150816132215/@comment-25626003-20150816170532

The mere idea of Yin and Yang was introduced a while after Part II started. I have no doubt in my mind that medical ninjutsu is Yang Release just based on logical deductive reasoning. Kabuto, Sakura, Ino, Karin(though not listed as an official medical-nin, still uses medical ninjutsu), Tsunade, Rin, along with even Hashirama and Orochimaru all use medical ninjutsu and are all confirmed Yang Release users. Perhaps there are some that think Yin Release is involved somehow.