Kamui was born in the Land of Water. His father was unknown and his mother was a wanted fugitive in the Mist village. Kaiya and the boy moved around quickly and often. Things would be quiet at first. Good even. But somebody would always end up making a huge fuss about his white hair. That's usually when they'd move again.
This time they were traveling between the borders of the Land of Water and the Land of Fire. Kaiya’s face was shrouded and she provided Kamui with one. She kept them mainly off the roads and just near the treeline. The path ahead seemed to start to close up and get tighter, focing them into the road. As they were just about to pass, leaves rustled off in the distance and before them stood two dark haired men with scars all over theirs faces.
Kaiya placed her sack on the ground and told Kamui to stay quiet. The taller man spoke first and told her to hand over their money and valuables if she didn't want her son to get hurt. He glanced at the boy and noticed.. something... his hair! The man drew a kunai and demanded Kaiya to tell him the boys name. Kaiya told the man Kamui was an orphan from the land of snow. She found him and was now his caretaker.
"Lies!" The man said. "That boy has the hair of a demon... and the blood of a demon! Ain't that right, Kaguya?!"
Silence frozen the room when suddenly Kaiya kicked her sack up and drew her sword out from the opening. She tossed a smoke bomb on the ground and threw a swarm of shuriken at the two men before here. One man yelled as she turned and reached for Kamui before taking off in the opposite direction. The men emerged from out out smoke cloud and gave chase.
They were about 10 meters behind Kaiya when one of them shouted, "Earth Style: Mud Swamp Jutsu!"
The ground before them would quickly turn into mud and a large wave of the liquid dirt would form, leaving a the area covered in mud. Kamui looked back while his wrist was being pulled by his mother. He would see this giant wave gaining on them and alert Kaiya. She would immediately stop and throw the boy out of the way, weaving a string of hand seals.
"Water Style: Great Floo-"
The wave slams directly into her and she is covered shoulder deep in the swamp. Her vision is blurry but she can make out two figure moving closer in front of her. The two men approach Kaiya, and focus their chakra to stand on the swamp.
"Where is the boy?"
Dazed, and her lungs filled with mud Kaiya just looks at the men blankly.
The sound of feet running on wood could suddenly be heard before Kamui appeared on top of the shoulders of one of the two men. He wasted no time before jabbing his fist against the rogues head and shot a 12-inched bone spike through his temple. The man dropped lifeless into the swamp.
Kamui sunk in as well, and stayed submerged to hide his location. The other man was speechless. It all happened so fast!
"What?! Tenzu!!" The man let out of cry of genuine pain over the loss of a comrade.
"Forget the money... I'll kill you both!!" The man furiously weaved a string of handsets. He reached down and placed his palms on the surface of the swamp. "Earth Style: Condensed Earth!!"
In almost an instant the muddy swamp became solid ground again. This great change in pressure would be enough to crush Kaiya’s ribcage and puncture a lung in the process. The only sound that could be heard as she slowly suffocated was a quiet, high pitched letting go of air.
The man smiled at Kaiya’s current state and assumed far worse for the boy who was completely submerged in the swamp. He had turned and began walking away when he felt a sharp pain in his ankle. He immediately fell to the ground. Once he gathered himself, he'd realize shuriken had been thrown into both his ankles. Except these shuriken were white in color and almost looked like they were carved out of teeth.
Kamui would suddenly burst out of the ground before the man, lightning covering his fist. He'd run over to the man and quickly slit his throat.
The threat was eliminated, but his mother was lost. Kamui walked over to her and sat there for some time. He'd dig her out and perform a proper burial for his sweet mother, who protected him until the end. The only person who showed him love. He kept her sword for memory.
Kamui would raise himself for the next years of adolescence. Surviving off the land and honing his skills. He would find himself near the Sound village gates when approached by a mysterious woman. She told him that the village was looking for strong, capable shinobi. And Lord Orochimaru had big plans for any who'd serve. Kamui wasn’t interested in serving anyone, but it did sound like an opportunity. He agreed and was enrolled into the Ninja Academy.