"What about my chakra? It's no secret that my sharingan leaves me with less than an optimal amount." he pointed out seriously.
I scoffed "You think I hadn't taken that into account when deciding on this? Sage mode can more or less be simplified to a ratio of natural energy and chakra being mixed together. The mistake that everyone seems to have is thinking that this means they gain more energy then they have and thus the state runs out quickly as they burn through their supply. The truth of the matter is that your store of energy doesn't change at all by achieving sage mode beyond the passive enhancement you body receives. This indirectly causes your chakra amount to grow but that's basic chakra growth theory and mostly dismissible." I explain easily.-
"So if I were to treat my chakra as a precious resource like usual I have nothing to fear then?" he asked for clarification and I nodded.
"Before you go thanking me for the opportunity or anything I need you to understand that the ONLY reason I am willing to do this is because it's for the good of the village, the fact it will also get my sensei off my back about taking students is just a happy coincidence." I said with a wink and he chuckled.
"I suppose all that's left is to ask when we start then." he said and now it was my turn to chuckle.
"Oh we already have." I said with a grin.
"WHAT!?" he exclaimed in shock.
I laughed "For all the good your experience in the Anbu gave you you failed to notice a key detail. I told you what this place was but you seemed to have failed to figure out what that means. By now your natural chakra circulation has drawn in quite the amount of natural energy, try moving and you'll find it rather hard." I said with a smirk.
Kakashi immediately tested that theory by lifting his arm and an alarmed look crossed his face when his arm creaked and proved barely responsive.
"Relax, calm your mind and focus on your chakra. Feel how is flows, how theres something else mixed in it. Focus on pushing that thing out without letting more in." I spoke calmly and the man breathed out and did as I instructed.
Admittedly I had played a bit of a trick on the man as the truth of the matter was that all beings absorb natural energy since birth which is why no one can sense it most of the time. It's a bit like how you can't really feel the air on your skin until it moves but times like a hundred. Usually the concentration of natural energy around someone is not enough to bother them but this chamber had a density of the stuff so high it had a physical presence to it. Naturally most people would start showing ill effects if they stayed too long, like say now.-
It was for this exact reason I purposefully made sure Karin or my sensei didn't stay here long whenever they came for whatever reason. Karin especially as I had noticed that she had been slowly acclimating to the dense natural energy found in my home that while harmless was higher than normal by a good deal. In a manner of speaking her body was slowly priming itself for sage mode as it became more tolerant of the energy. Not to say she'd just up and achieve it randomly one day but that it was not inaccurate to say her body was growing a strong affinity to the energy much like how someone who works out adapts to the work out making it easier for them.-
Her exposure to the natural energy is more or less "exercising" for her body and so she is getting more tolerant to it as time goes on. Honestly speaking if she had another year at this rate I could teach her sage mode laughably easily as her body would already be highly tolerant to the natural energy needed. Even more unfair was that thanks to her bloodline she was already an incredible sensor and so sensing natural energy would be easy once it was pointed out to her.-
Anyways Kakashi was sweating heavily as he tried his hardest to sense the natural energy that had invaded his body and expel it but was failing horribly. The moment the petrification started to mineralize him I slammed my palm into his chest and for a brief instant a green energy was visible as the natural energy shot out of his back.
He groaned in pain "Was that necessary?" he asked rubbing the no doubt bruised part of his chest.
"Would you prefer turning into a rock cuz I could always wait till you are on the brink from death next time if you'd like?" I asked with a grin.
"On second thought I think I prefer the bruise." he said nervously.
"Good to hear! Now tell me what you've learnt after struggling against the natural energy that crept into your body." I said turning serious for the second part.
"It was like try to fight a poison that I couldn't sense at all, if it weren't for the sort of absence of chakra it left in my network I wouldn't be able to notice it at all." he said with mild horror at the memory.
"I'm not surprised to hear that, natural energy without special sensor training is nearly impossible to notice and because of the fact it doesn't truly damage the body no one would feel it until it was too late or they had a talent for it. This is why sages are as rare as they are, the energy lulls the unprepared into a false sense of security they don't survive. That was the point of this little lesson of mine, to make sure you understood that until I say otherwise you aren't to try anything with the energy alone." I said honestly a firmly.
He nods "I understand, what's next?" he asked curiously.
"Now I'm actually going to teach you something, the first thing a sage should know in my opinion. How to sense natural energy. You are familiar with the twin energies that make up chakra yes?" I asked and he nods.
"Spiritual and physical energy right?" he asked and I nodded.
"Yes and this is VERY important for sensing natural energy. Natural energy requires that you use your spiritual energy alone to sense and even then it takes serious concentration since you don't know what you are looking for at first. Imagine it like being blind all your life and suddenly being able to see. At first you wouldn't be able to identify any colors because you can't describe a color without having seen colors, it doesn't work. In this case natural energy as well as the other energies are just different colors and you have to figure out which one you are looking for." I explained seriously.