Can a boy ninja kill a ninja master?
I feel that it is my duty to refer your ninja question to www.realultimatepower.net.
Without clicking on your link, I’ll go on record as saying I find it difficult to believe that a child could beat a master of any fighting skill (martial arts, boxing, wrestling, what have you), much less kill him/her.
Unless said child killed said master in some other fashion, such as shooting him/her.
Which considering that, despite all the romanticization, ninjas were nothing more than professional spies/assasins, killing someone in such fashion would be the true ninja way to take care of business. Though I recon that burning his house down while he’s asleap would be keeping more with the tradition.