Quote Originally Posted by pandaofthebamboo View Post
maybe it blends with the normal chakra of his body
Chakra, if there's a transmiter( the one sending the signal/chakra) and there a receiver (Pain's Body). There must be a way to figure out where it come from with the sharingan. I mean sasuke could see Deidara's microscopic bomb filled in the air/inside of him so unless the transmiter is sending the chakra directly/instantly to the receiver, it another plot hole no jutsu