Since orochimaru doesn't know the chakra we can rule out Kabuto, imma take a wild guess and say Its Madara's brother who thinks Madara has gone out of control and will aid sasuke.
Btw did Madara really just conveniently spit out those weapons on Guy? That's some crapy writing right there
Btw did Madara really just conveniently spit out those weapons on Guy? That's some crapy writing right there

its crazy man. I mean he aint even trying. The ONLY saving grace was Guy.... I hope its a lot of taijutsu and I can't wait for Rock Lee to jump in as well (hopefully)

