Naruto: The Birth Of Fenrir and his Keeper

In the many weeks that followed his appointment as Kazuki's trainee, Keitaro found that he had grown to have a very distinct dislike, maybe even a budding hatred, for the concept of studying. 

He had thought that the few years of studying that he had been doing ever since he could actually read would have been enough for him to show off his knowledge and skill to a certain extent, even if it wouldn't be considered much in the eyes of true masters of their respective crafts.

Yet all it took to completely curb his hubris was two weeks of studying with Renji.

Unlike him, who was technically a much more mature and experienced individual who was able to focus, and absorb info in a much more efficient way than any five or six year old had any right to be thanks to his twenty plus years of life, Keitaro still found himself falling behind Renji ,who, while technically being older than him by a few years, was still very much a child!

It was rather embarrassing for Keitaro how quickly Renji was seemingly capable of comprehending massive stores of information, compared to himself. While Keitaro had been practically deluding himself with thoughts of being a genius for his age, Renji allowed him to see what a true genius was actually capable of.

Complex and advanced mathematical theories, things that those with PHDs and doctorates would spend years debating over, were nothing more than simply morning exercises for Renji. 

Understanding the intricate relationship between the various physical elements that formed the building blocks of reality, and the basis for most of chemistry, came naturally to him, and there wasn't a single specimen that Kazuki and brought for them to dissect and annotate, that Renji couldn't do with one hand tied behind his back. 

The amount of information that they were forced to deal with on a day to day basis was astounding, especially given that they hadn't even touched on any actual ninjutsu as of yet!

Of course from Keitaro's point of view, there was still quite a bit of info that would have been deemed as common knowledge in his previous life that simply wasn't known in this one, simply because of the time period and the fact that they weren't discovered yet; but even then it was still impressive how much knowledge Renji was able to peruse through and comprehend without much trouble.

Of course with his son's spectacular performance as a precursor, Kazuki seemed to expect a similar level of progress from Keitaro, and it was taking his all just to not fall behind with the workload that had been forced onto him. He was already doing extra reading and studying so that he could fill in the proverbial holes in his knowledge base that Kazuki deemed to be glaring problems for his future progress, and that was all while also taking an active role around the laboratory as Kazuki's assistant. 

Though he had already come to terms with the fact that the title was more so a symbolic one than anything else, Keitaro still found himself all throughout the lab from time to time. 

The only things he had actually been doing around the lab had been cleaning and the putting away of the tools, as well the laying out of the apparatus in preparation for minor experiments and such. Though it was repetitive and rather boring, Keitaro didn't complain about it because it was truly the best way for him to learn the ins and outs of things at the moment.

By taking care of the cleaning of the lab, he got a chance to familiarize himself with some of the machinery and tools that were sprinkled around the lab. Not to mention that he also got a chance to interact with the many different types of chemicals and compounds used on a day to day basis.

 It was imperative that he understood the correct disposal method of the various chemical concoctions as well as why they were handled a certain way if he didn't want to accidently cause an explosion. 

Thankfully he had only caused one minor accident where he accidently created a cloud of poisonous gasses when he had first started, though the researchers had all been more interesting in testing the potency of the poison cloud than scolding him, which only further cemented the idea that researcher and scientist were weird in his mind.

The duties he performed around the lab also helped to cement the theoretical knowledge about certain things that he had been studying since he could 'play around' a bit with some of the solutions and test subjects before disposing of them. A practice that was encouraged by Kazuki as a way to not waste precious materials on impractical experimentation.

It was grueling but rewarding, as Keitaro felt that he was taking steady steps towards his goals with every passing day. That idea was only further reinforced once he had also begun to take part in physical training under the careful guidance and care of Kazuki.

It wasn't anything amazing, just general strength and stamina building exercises, but it was only a matter of time before the real training began, and Keitaro couldn't wait for it.

With a tired grunt, Keitaro threw down the small satchel that he had been carrying around for the last few hours at the base of a tree and propped himself up on the tree as he caught his breath. The satchel wasn't ridiculously heavy, as it only weighed about twenty or so pounds, but running around the training field in the hot sun while wearing it was more than enough to make Keitaro despise the sight of the satchel in question.

"You managed to shave off another couple of seconds off of your time yet again." Said a smiling Kazuki as he peered down at the sweat drenched Keitaro from his perch in the tree.

"I might just have to increase the weights that you're using much earlier than I thought I would have needed to if you keep improving at such a steady pace."

He dropped out of the tree and landed next to a disgruntled Keitaro who immediately refuted him.

"Why would you do that?" he asked while struggling to catch his breath, "I'm barely managing to reach my target time as it is, more weight would make it impossible for me"

"You definitely won't make it with that sort of attitude," Tsk Kazuki and he tossed a bottle of water towards Keitaro.

"The whole point of training is to push you beyond your limits. It loses its effectiveness if you aren't constantly pushed to the extreme."

While Keitaro could understand that line of thought, it didn't mean that he enjoyed it too much. 

He had been spending most of his days either training from morning till evening, or studying in the lab with Kazuki or Renji. He hadn't had a day of rest in quite some time and was about ready to rebel against the tyranny of his slave driver named Kazuki.

"You say that but I don't see you pushing Renji as hard." Said Keitaro as he looked off to the side.

Renji was currently running through an obstacle course. It was a collection of bamboo poles of various lengths and thicknesses. These pools were extending from out of a rather deep pit that was filled with mud. The wooden poles were spaced out irregularly throughout the pit with several contraptions that would occasionally spit out wooden kunai and wooden senbon needles at random times. 

The aim was to run through the bamboo poles without being hit by the random projectiles, reach the opposite end of the pit to collect the flag that was placed there, and then return to the original starting point of the obstacle course.

While it would be difficult for Keitaro to do such an obstacle course given that he was rather new to the whole shinobi life, Renji who had been training for at least four years by now was having quite an easy time at it.

As he watched Renji swiftly and easily weaving his way through the wooden poles, dodging any and all of the projectiles sent his way with relative ease, Keitaro couldn't help but begrudgingly admit that Renji was pretty good. He didn't even pause for longer than a second in order to collect the flag, before he was once more weaving his way back to the starting point of the obstacle course.

 He even had the cheek to do a backflip in order to exit the obstacle course and bow towards Keitaro and his father, seeing as he had noticed that they were watching him at the moment.

"Hmmm, you might be right. If he's so easy going as to do an unnecessary back flip like that, it might be time I upped his difficulty just a bit." Muttered Kazuki as he tapped his chin in contemplation. 

Keitaro couldn't hide the smirk that flittered across his face at Kazuki's words, and couldn't wait to see Renji's face once his training suddenly bumped up in difficulty.

"Anyway, you're improving pretty quickly Keitaro and once I'm satisfied with your stamina, we'll begin working on your strength and speed training."

 Turning towards Keitaro, Kazuki poked the satchel filled with weights.

"Also, while I know that you are tired, you're supposed to be wearing that for the entire duration of the training time." 

"Ugh, but it's hard to breath when I wear it." Complained Keitaro, though he still picked up the satchel and clasped it around his body.

"That's all a part of the training. The weights are for building your stamina and strength, but the restrictiveness of the satchel will force you to increase the efficiency of your breathing. Not to mention it'll help you with getting accustomed to handling yourself when you're exhausted. There are a lot of times where as a shinobi, you'll find yourself exhausted while running away from enemies or while running after them. You'll need to be able to collect yourself quickly and recover your strength in short order, so that you'll have more options available for you to pursue when need be." 

Kazuki kneeled down so that he could check on the satchel, making sure that it was secured properly and not being too restrictive, before patting Keitaro on the shoulder. 

"This is just the basic training that I'm putting you through right now, and while I'll admit that it is rather strenuous, I'd much rather you suffer during our training sessions, than for you to end up suffering out in the field because I didn't push you hard enough. Your father entrusted your training to me, and while I can't promise that I'll be able to prepare you for everything, I'm going to do my best to try."

"I know, I know, still doesn't mean I can't complain a bit about the training." Mumbled Keitaro as he turned to continue his laps around the field. He still had a few more to go and while he could have waited a bit longer in order to have a longer rest period, he also wasn't the type to take a half hearted approach to his training.