haku first appeared dressed up as a hunter-nin. hunter-nins wear maskes to hid their faces with symbols to identify which hidden village one is from. their job is to dispose and destroy bodies of nins so as to prevent other nins from studying it. a shinobi's body is full of vital information. from it, other ninjas can learned the dead shinobi's jutsus and village's secrets. haku first appeared as a hunter-nin who seemed to have killed zabuza with needles thru his neck. he thank kakashi and told him that he had been looking for zabuza to kill him. then he went off carrying zabuza's body.

there has been some contention in forums whether haku was indeed a hunter nin or not. i brought up this topic, presenting haku being a hunter-nin as a potential plothole. i asked when did haku became a hunter-nin. some offered that haku was never a hunter -nin and he just pretended to be one so he could get zabuza's body after he was defeated by kakashi. when asked where he got the mask, others opined that he must have gotten it from one of the hunter-nins who must be after zabuza. but, i counterject, haku said something about how the mask reminds him of the old times. again, they opined that maybe his father was a hunter-nin, who afterall did kill his mother. i still remain unconvinced. haku was an expert on acuapuncture, he knows the body inside out, a skill all hunter-nins should possess. so it's really really likely that he was a hunter-nin. well you could say that maybe he learned it from his father. but he was just a little kid when he was abandoned about 5 or so. this am wondering about too. how could they let haku wander about when they know he was of advance blood? could be that his father never told the rest of the village that half of his family was of an advance blood since he himself might get killed? neeways i still think haku was indeed a hunter-nin but when did he became one was a plothole. but i myself eventually find this little hypothesis a bit lame afterwards. the most probable explaination (and this was also brought up by somebody in the forum i go to) that he probably got he mask from some hunter nins who was after zabuza, probably not long after the two ran away from their village. since then it was probably his habit to dress up as a hunter-nin and butt in the nick of time everytime zabuza-san gets into a tight spot. yun lang... :P