Quote Originally Posted by Y View Post
EDIT:

As was pointed out in IRC, you do in fact have to "sustain" the Kagebunshin; Kakashi comments that because he is weaker than Naruto he cannot keep the Kagebunshin up for long.
Yes that is right. Also when Naruto fought Neji in the exam. Neji was able to notice that the real Naruto always stayed back and he dashed past the clones to hit the real Naruto! Well Neji thought he did but instead Naruto purposely held back a clone to fool Neji.

However, Naruto seemed to purpose dispel his shadow clones to further trick Neji into thinking he hit the real Naruto. Thus it must be a known fact that Shadow clones fade away or die when the main user is really injured, knocked out or killed etc. If not Naruto would not have known to even try that. And Neji would have also have noticed to if clones started to fade away for no reason... instead of trying to attack Neji to protect the real naruto.