Messing with Kakashi aside I wasn't actually being deceitful as whether it was relative to the normal time it took to learn sage mode or in general this training shouldn't take very long at all. Maybe a month in total if Kakashi doesn't slack off. Compared to the years it normally would take this was ridiculously fast. In peaceful times like now a month was also quite a short amount of time to grow to such a degree. I also wasn't being generous with my timeframe either as I truly believed that with his talent and my serious help Kakashi could do it in this amount of time.-
His eyebrow twitched at my reply but he just sighed before asking "So what is the next step now that I can "see" natural energy?"
"Now you need to learn how to tell it apart from the rest of the energies in the air. Close you eyes and extend your spiritual perception out and I'll make this step particularly easy." I commanded and he obeyed.
I nodded pleased to see that this past week had been exactly what he needed to get a better understanding of his own spiritual energy. I doubt he even realized that he had improved so much in the field as his spiritual energy extended smoothly out from his body in a radius of several feet in all directions. I casually transformed the dense natural energy flowing through his spiritual energy into various shapes and symbols and Kakashi focused his spiritual energy on that part of the energy. When he started trying to exert his own control on the stuff though I didn't hesitate to shoot a spark of lightning release at him making him yelp from the sudden pain.-
"I told you to focus on the energy, not try and mess with it haphazardly." I scolded him sternly. "You barely managed to perceive the stuff after I purposefully made it stand out much less reached the level necessary to start controlling it. Try something like that again and I might let you face the consequences without stopping you." I said firmly.
"I'm sorry. I got ahead of myself, it won't happen again." he said sincerely.
"Good, now try again while I increase the difficulty." I commanded and he did.
Increasing the difficulty in this case was making less obvious disturbances in the energy and having him try and spot them.
Once I was satisfied with his accuracy at that I decreased the disturbances even further forcing him to try even harder. Metaphorically speaking I started out with an elephant and was slowly reducing it down to a flea. The first was naturally easier to see but the last was much much harder. I had learnt the method that Katsuyu and the other two major sage regions used to train their sages from the slug sage herself and found it.... inefficient. My reason for saying so was that they settled for "good enough" natural energy sensing before moving on but that was making the process of learning harder.-
Even Jiraiya who had years of training and experience with sage mode hadn't "perfected" it yet and couldn't sense another sage unless they made it obvious or he actively tried to sense the natural energy around him. I know because otherwise he would have spotted me the moment he met me as my state while not obvious wasn't very hidden either. Thing was though that in order to get the sort of control needed to have "perfect" sage mode you also needed to be able to passively sense natural energy without really trying but the toads clearly failed to tell him this or didn't realize this was the case.-
To put it bluntly Jiraiya's sage mode was horribly performed because of his faulty training. I refused to make that mistake for Kakashi and so I was forcing his spiritual perception to grow so acute he'll be able to sense and control natural energy in an instant. It took five days of training for him to grasp natural energy with his spiritual senses with ease at the low low price of being sleep deprived and mentally weary.-
"Your first step towards sage mode is now complete, take the next two days to rest up and recover." I said not tired at all unlike the half zombie Kakashi.
I only needed three hours of sleep to be fully refreshed after all but after five days of barely getting five hours of sleep the silver haired man was dead on his feet tired. Was I being a bit cruel with this training schedule? Yes. Was it worth it? Absolutely! Thanks to this training even while dead tired Kakashi could immediately sense natural energy in a precise manner, just imagine how he'd do while fully rested.-
The next two days went by quietly after that and then Kakashi showed up at my home yet again and I tested him by having a tiny prick of natural energy buzz by his ear and he swat at it absentmindedly. It took him only a moment to realize that it was me messing with him as the buzz didn't vanish.-
"Is that really necessary?" he asked complaining.
"Absolutely! The fact it's also amusing is just an added bonus." I say with a grin.
"Fine fine, I know better than to argue at this point. What's todays torture?" he asked half joking half not.
"The next week will be spent forcibly boosting your bodies tolerance to natural energy. Not going to lie it's going to suck hard for you." I said honestly.
"And if we didn't force the issue?" he asked hoping for a way out.
"It'd take you about half a year to get to the point you don't immediately risk turning to stone when drawing natural energy into your body. Then another six months to get to a point where I'd allow you to attempt sage mode." I said bluntly.
"Torture it is then." he said with a sigh.
"Glad you understand, now follow me back to my meditation chamber." I say before heading back to the crystal chamber.
He followed behind me but couldn't help but sigh in relief once we got there. I gave him a knowing look and he just chuckled embarrassed.
"After getting used to being surrounded by so much natural energy spending two days in the rest of the village that lacks the stuff in more than minute quantities is a disconcerting feeling I know. I've had my entire life to get used to that feeling, you've had barely two days. It'll pass in time I promise." I say reassuringly.