Thanks to the forceful adaptation to natural energy he had received Kakashi was able to resist the fossilization that started to occur as the present natural energy was drawn into his body. Instead he focused on trying to fuse the energy with his chakra and it was rough going. Not that I expected him to accomplish it on his first attempt to begin with. In a manner of speaking a normal shinobi entering sage mode required a lot of effort as they were effectively doing four things simultaneously.-
The first was drawing in natural energy without getting flooded with the stuff. The second was keeping the energy they drew in from rampaging and turning them to stone or in the case of the other sage regions an animal. The third was trying to control the natural energy into fusing with their chakra. The final was keeping their mind focused on these tasks as a moments distraction could mean failure or worse. For me all of this happened on it's own as a matter of course so I didn't need to pay it any attention at all unless I went for saint mode.-
When I deemed him too close to turning into stone I slapped Kakashi on the chest forcing the natural energy out of him and resetting his state so he could keep trying without risk. He only took a moment to center his mind again after the sudden pain of my action thanks to having experienced it plenty since I started his training. It took thirty resets for him to briefly create a spark of sage chakra that winked out as fast as it came.-
"That's enough for today. Go home, eat well and rest. We'll meet up here at dawn tomorrow." I said calmly and he breathed out tiredly and nodded.
This process was heavily taxing for the mind and not a little stressing for the body as well so after so long maintaining it he needed rest. I could have allowed him to keep trying if we were in a hurry at the cost of the backlash being much greater after he finally relaxed but we weren't in a hurry so this was the ideal pace. The next morning when the sun had just started to light up the world I was waiting on top of the Hokage monument when he arrived perfectly on time.-
I didn't plan to point out how out of character for him this was as he was ALWAYS fashionable late. I could tell that he was serious about this training and I had no reason to be dissatisfied so I left it alone. While the world was awakening we restarted his training and it was clear that the rest was exactly what he needed as the process was much smoother this time though it took him another three resets to spark up sage chakra again. It only took another five resets after that for him to find the perfect ratio of energies for him and start truly creating more and more sage chakra.-
Red markings began to appear around his eyes while his hair spiked up and he began to take on doglike properties.
"That's far enough. Open your eyes and test your changes, you are currently in sage mode." I said with a smile and he did as I said.
"Incredible! I can smell everything for miles and my hearing is so much more sensitive now! Do you feel like this all the time!?" he asked in amazement.
"Not precisely like what you are feeling as it's clear that your sage mode has taken after your dog summoning beasts whereas mine could be considered as truly neutral and thus all inclusive. Still congratulations are in order for officially stepping into the rank of sage." I said with a smile.
"Thank you, truly. I know that without your help I would have never achieved this." he said with a sincere bow.
"Bah! Your trainings not over yet you know?" I said with a chuckle while waving off his thanks.
"What more is there?" he asked confused.
"Your sage mode is imperfect and primitive at the moment and you have no idea how to use sage arts. You'll need my help to learn these things still. Perfect sage mode you can probably learn on your own with enough time to practice but it'll be faster if I help. As for sage arts you will definitely need my help with that." I said honestly.
"No more bruises though?" he asked suspiciously and I chuckled but nodded.
"It's a matter of refinement to perfect your sage mode and sage arts are a matter of understanding how much energy to add to your jutsu in your new state as well as taking advantage of the improvements your body gets. For the sage regions this is the kata's and specialty techniques of the sage modes they give. Jiraiya for example learnt toad oil techniques and toad kata fighting style." I explained calmly.
"I see but what would I learn if my sage mode is related to my ninken?" he asked confused.
"Well if I had to guess your sage mode increases the strength of your speed, hearing and sense of smell like that of a ninken and perhaps even further. So your best bet would be to learn how to utilize these traits to the best of your ability, the Inuzuka taijutsu and techniques are probably the perfect fit for you in this case. In fact they fit so well that I can't help but wonder if the clan had a sage at one point with a sage mode like yours, could be a coincidence though." I said with a shrug.
"Ah, well I guess that makes things easy for me as my mother was from that clan so I already know some of their techniques." he said with a amused look as his sage mode faded.
I wasn't surprised that it hadn't lasted very long as I had stopped him from gathering too much sage chakra lest he permanently take on traits of it's imperfect form like how Jiraiya had a large wart on his face from a similar past problem. The markings faded from Kakashi's face and his ninken features went with them returning him to normal.