A/N: For Writing Prompt #6 on /r/NarutoFanfiction (you can see the other entries at redd dot it slash 4sq3fx). "Something or someone besides the Kyuubi is sealed inside Naruto."
Warning, the third part is slightly nsfw (nothing explicit, but, how do they say it? 'Adult themes')
"I won't let you hurt my precious people!" Naruto shouted, facing down Mizuki. His world had narrowed to just the clearing. Behind him was Iruka, injured and in need of protection. In front of him, the traitor Mizuki, in need of stabbing. Lots of stabbing. Beyond that, branches swayed and undergrowth rustled, but any reinforcements would be from Konoha, so he wouldn't have to worry about being flanked.
He brought his hands together, hoping against hope that the technique he'd learned but not practiced yet would work. The seals felt natural, and he finished the last one a heartbeat before Mizuki's kunai pierced his throat.
In a puff of smoke, he disappeared, and a new Naruto came out of where his stomach had been. It drew a kunai and cut out at Mizuki, drawing blood on the side of his leg. When he struck it through the head, *yet another* Naruto appeared, again from the stomach area.
Iruka wasn't sure if it was the blood loss, but it seemed as though Naruto was creating shadow clones - a high-level jutsu that the dead last of the class should never have managed to learn, let alone in just a few hours!
Naruto stepped back, throwing a handful of shuriken. Mizuki was disoriented enough that two passed through his guard and into his shoulder, spattering bright red drops of blood on the forest floor. He lunged forward and killed Naruto for the third time in the fight, leading to *yet another* puff of smoke, and new Naruto appearing.
Much later, a dead chunin renegade lay before an orange ninja who looked fresh as a daisy. No injuries, no dirt on his clothes – not even out of breath. He formed another set of hand seals, closing the seal on his stomach again, and went over to Iruka. "Let's get you to the hospital. Don't talk, I'll explain on the way."
Naruto carried the near-comatose body of his teacher as he leapt from branch to branch, hoping his makeshift bandage would hold. He tried to distract himself and his cargo from the blood slowly dripping down his back by talking about the earlier fight.
"I couldn't get the shadow clone to work, but I saw a technique that seals a clone into you – except you are the clone. Or something like that, I didn't really understand the explanation. Anyway, you need a special seal, but it turns out I already have one like that. What a random crazy happenstance! So, I just used it when Mizuki attacked me, and whenever I died, the shadow clone sealed in me popped out!"
The Hokage leapt down beside Naruto, motioning for a pair of ANBU to take Iruka to the hospital. "That's a great technique Naruto, but what would have happened if Mizuki had managed to kill all the clones and reach the real you? Isn't it a dangerous technique, because it teaches you to let yourself get killed in exchange for small amounts of damage? How many clones do you have sealed inside you?"
Naruto laughed, and said, "That's the secret, old man. It's shadow clones all the way down!"
The two chunin candidates faced each other in the arena. Around them, the stands were filled with cheering and screaming people, here to see the very best and brightest face off against each other. The proctor raised his hand, the tension mounted...
"Begin!" The proctor's hand fell and Naruto and Neji both stepped back, forming seals.
Neji used the Byakugan to peer at Naruto. He'd seen Naruto's technique in the preliminary rounds, so he knew a little of what it did, but not how to counter it. Looking into the seal, he saw... another Naruto, with the same seal!?
Frantically he looked down, down, down the endless stream of Narutos, each with the same seal and containing a seemingly endless chain of clones. He heard Naruto step forward, but the clone he was watching didn't move. Neji pulled back, looking up the chain this time. He was feeling dizzy and slightly sick, and couldn't tell which Naruto was the real one any more.
Naruto walked over to Neji and, with his left hand, lightly shoved him. Neji fell over, all sense of balance gone.
Neji cancelled the Byakugan, snapping back to reality, just in time to realise that falling over handn't been a bizzare vertigo-induced dream.
"Winner, Naruto Uzumaki!"
Naruto burst into his home, frantically getting ready for his date. He dressed himself quickly and grabbed some deodorant and a toothbrush, then raced into the bathroom. Looking at the clock, he scowled. No time!
He formed a set of seals, then stabbed himself. After he reappeared in a cloud of smoke, he checked the mirror quickly before sniffing under his arms. Who knew that the jutsu defined 'harm' as everything unwanted that was in or on the body? He didn't even need to use the loo any more!
Naruto went to the date, much calmer now. After he and Sakura had shared a nice meal, they went for a walk along by the river. Soon they were chatting and laughing, and soon after that...
Naruto and Sakura had found a private part of the riverbank and were doing private things there, when Sakura decided it would be an appropriate idea to lightly nip at Naruto's neck. One puff of smoke later, and a calm, composed and clothed Naruto sat on the ground in front of her with a sheepish look on his face.
...and after that, Naruto was very careful to never walk around with his seal accidentally active.
