All in all, not too challenging for him, but not exactly a walk in the park. This would take time, concentration, and all of his equipment, which he had left at home.
Not resigned to lose his day in the training grounds, he tucked the book under his arm and neatly folded the letter into his pocket, before setting off into the woods.
Naruto loved to explore, although the ANBU would never let him when he was little. He understood why they wouldn't let him go. You can't just let a toddle wander off by himself, but his stubborn attitude never let him give up that desire to just see what's out there.
The first time he had come here, he had been so excited to discover the multitude of used kunai and shuriken that littered the training ground. When he ventured deeper into the forest, he would only discover more and more kunai lodged into the branches of trees and burn marks left over from fire techniques cast long ago.
Naruto had already scavenged most of the stuff left around. He didn't particularly like using partially damaged tools, but it wasn't exactly a choice. With the prices that the shop owners were charging him, it was better to resort to the supplies he would find in the training grounds.
Today, Naruto found himself traveling further and further into the woods than he usually went, hoping to find some kunai or shuriken that he may have missed before.
After about 45 minutes of walking with no results, he was ready to turn back and head home to unlock his new book. As he turned to leave, a glint of sunlight caught his eye. Up in a tree off to his right, he could make out the metallic gleam of a kunai's handle.
Naruto smiled to himself as he set his book down and began clambering up the thick trunk. He slowly inched himself up the bark, until he could finally stand on the wide branch and get a good look at it. The blade was buried hilt-deep inside the bark. Naruto took hold of the handle, which was bigger in comparison to the other kunai he had used, and pulled with all of his might.
After three of four tugs, he finally managed to yank out the blade only to discover something different.
"The hell is this?"
The blade wasn't shaped like normal kunai. It seemed to have three prongs that shot out from the handle. Speaking of which, he had never held a kunai with such a bulky handle.
"Aww man, the thing must be broken," he pouted to himself and got ready to chuck it away, when he caught sight of something on the handle.
Naruto was no expert, but he certainly recognized an advanced formula when he saw one. He ran his hand along the handle, rubbing over the complex formula he had never seen before. His eyes darted over the kanji, and he couldn't make heads-or-tails of it. With his limited knowledge, he could only pick up bits and pieces it.
This was more advanced than anything he had seen in his books. It was something unknown, and that sent an exhilarating chill down his spine.
Now this was what he considered a challenge. While jiji's seal was complicated for an average beginner, he would have it solved within 15 minutes, maybe 10 if he was really pushed. That would be a breeze considering the security seal was timed to collapse in after an hour.
This was something new, and it could possibly take him years to figure out. Never one to back down from a challenge, he tossed the kunai in the air, liking the way it felt compared to others, before making up his mind. A big grin found its way across his face as he slowly made his way back down the tree. He picked up his book and started to make his way back to the village, his eyes never leaving the mysterious formula on the weird kunai.
2 years later
The blonde ten-year-old sat in the middle of the clearing, moving with as much precision he could muster. Slowly and painfully, he weaved and flicked his brush across the parchment, leaving smooth, clean strokes in its wake. He brought his arm down for the final stroke and slowly began to draw the final kanji, all the while pumping as steady a stream of chakra as he could manage.
Finally, he finished and gazed upon his work, letting out a sigh of relief. A smile erupted on his face. He opened his mouth to shout, "Yatta!" only for the seal to explode in his face, sending him skidding back several yards.
"...oww, " was all the boy could groan, as he tried to sit up.
The entire front of his body stung and his goggles were clouded with soot. He tried to clean them with the back of his hands, as he mentally reprimanded himself.
He had left the tip of his brush on the page. When he had grown excited, a surge of chakra had ran through his body and, by extension, through the brush and into the seal, setting it off.
He muttered a curse as he dragged his aching body out of the clearing towards the cool shade of the tree line. He leaned back against the tree and winced as he inspected the damage. His hands were bright red, and several blisters were already forming.
Could have been worse.
He cringed as he remembered the first time he had attempted to make an exploding tag. Of course, he had set it way higher than he should have for a first attempt. The front of his shirt had been burned away, and the flesh on his hands and chest had been completely seared off.
That had been a very unpleasant day at the hospital due to his aching body and the scolding he received from the Hokage. Kitsune had dropped by and gave him his signature silent scolding, which was even worse. His aura and stare had made him feel even guiltier than when Iruka had come by.