Neji Hyuga can't remember a time before he knew Jyuuken style of fighting. His earliest memory is of his father drilling him in the basics, making him move in wide circles around his opponent. As a child born in a ninja clan, he's been trained in the art of killing as long as he can remember.
His first kill is made at fifteen years old.
It is his first mission after he is promoted to chunin, along with the rest of his team. They are to travel to the Land of Mist to deliver papers regarding a renewal of the non-aggression pact between the two countries.
Three days into the journey, they're ambushed by a band of masked ninja. Neji thinks that they are from Iwa, considering that there were still some who held grudges from the last war.
Their formation is simple. Lee leads at the front of the team, ready for anything. Neji, himself, stands at the back, using his Byakugan to watch their backs, leaving Tenten in the middle. Since she is a mid to long range fighter, and therefore out of the direct line of combat, she is the one to carry the scroll. Guy-sensei is separate from the formation, believing it would be a good experience for Neji to take charge.
The battle is going well so far. No bodies are on the ground yet, but a quick survey of the enemies' injuries verses their own, Neji would say that making a hasty retreat would be the best strategic move to make. A smirk sits on his face as the ninja he's fighting hesitates.
It's wiped off his face when he hears Lee calling out to their other teammate.
He whips around, not even bothering to notice as the one in front of him runs off. Tenten is hurt: in a last ditch effort, one of the enemy ninjas gets close enough in her guard to wound her with a short sword – ironically, one of her own. It throws her off balance: exactly what the ninja needs to finish her.
He doesn't get that chance though, because Neji manages to get between them in time. He yells in fury, moving so fast that the enemy ninja doesn't have time to react.
He lashes out, stabbing the man's body with chakra-enhanced fingertips. Neji doesn't just block the enemy's tenketsu, avoiding major organs, like he had previously. No, to protect his teammate, he strikes to kill.
His fingers apply more pressure than necessary at the most fatal point on the body: the spot right above his heart. The man sputters blood, spraying flecks of the sticky substance all over his face.
Neji doesn't bother to check if he's dead: it was a killing blow. But that hasn't even registered in his mind, because Tenten is lying on her back, unconscious. By now, all of the masked enemies are gone; all except the dead man behind him.
Guy-sensei and Lee rush over, the latter still yelling her name in worry. Guy immediately begins cutting away at the fabric of her shirt, tossing the bloody cloth aside as he starts to administer field treatment. Tenten has the presence of mind to crack a joke-something about how Lee is usually the first one to get injured-before passing out.
After her wound is bandaged Lee and Neji are sent ahead to the nearest town, about thirty miles away. They need to find a doctor to look over her wounds. Guy stays behind for a moment, sealing the dead man's body into a scroll.
Later that night, when Tenten is awake again after falling unconscious, she thanks him for saving her. Neji lets out a sigh, and tells her that he doesn't need thanks. Lee is quick to yell out his relief that she is alright, and that they have her back: because they're a team. Neji can see the flush on her cheeks from a fever, but the smile on her face convinces him that she'll be alright more than anything the doctor says.
When Guy pulls out the body to examine, he tells them to observe, and look for anything that may identify him. It finally occurs to Neji that he made his first kill. He shudders the the thought, and looks down at his hands. He stopped this man's heartbeat with nothing but his fingertips. Neji realizes, not for the first time, but it's still overwhelming, the power behind his bloodline. Tenten lightly places her hand on his, and he relaxes.
They find nothing on his body. Not even Neji's Byakugan can find any identifying marks. No labels on clothing, no distinguishing features, and no especially distinctive items on his person.
The rest of the mission goes off without a hitch. When they finally arrive back home, he's angry and a bit disappointed that he didn't get to beat more of those enemy ninjas.
After Tenten has her wounds checked out in Konoha's hospital, though, and she smiles, thanking him again for keeping her safe, Neji can feel his anger ebb away. He doesn't think about how fearsome this power is: the power to kill a man with nothing but his bare hands. For now, he is just glad that she is safe.