User blog comment:Lifebleedin/how does killua know zenos ability/@comment-24287488-20140123063005/@comment-24287488-20140128093902

@Bennlimos: Are you saying that if a person is made to stand in front of the Palace, he could not see the raining down of Nen dragons? If what you're saying is true then it is easily assumable that a normal person can't see the Nen devils created by Razor or Nen beasts created by Goreinu. To him, he can only see a ball flying in the air while playing with them, right?

Emitters and Transmuters are different. In cannot be used on emission techniques to hide the emitted aura while it is a different case with Transmuters. It is only usable as long as the aura is connected to Nen user. That's why Gyo has to be used to see if a Nen user is hiding something. Well, I think not all but some emission abilities can be seen by humans. And sorry, if I sound mean.