Kannin met up with Warai the day after that at her place and told her about teaching Kakashi to use the Sharingan. She was a little reluctant at first, but agreed in the end, if only out of guilt for what she had promised the night before.
"I told him to meet me at noon in five days at the old training ground, does that work for you?" Kannin asked, "Y'know, we could do something beforehand, to make up for Fugaku interrupting us last time..."
Warai's eyes widened a little with Kannin mentioned Fugaku, which he didn't seem to notice, but she said after a small pause,
"I think that could work. Maybe just some sparring to get the blood flowing--it's been a long time since we last sparred now that I think about it."
Kannin smiled and said, "It's been so long because you got tired of losing so much"
"Oh I did not, you liar" Warai scoffed
"Really?" Kannin said, pointing to his temple, "I have the tally right up here, you know: 23-15 in my favor."
"Oh you are full of it!" Warai said.
"Am I?" Kannin grinned
"If this is your idea of flirting, you've got a long way to go Uzu" She said, sticking out her tongue
"'Uzu?'" Kannin gasped, "You haven't called me that in years! I can't believe you'd stoop so low."
"Oh I can stoop lower than you could even imagine" she said, kicking him in the shin
"Exactly how low is that, Warai?" Kannin said with a devilish grin, "Mind showing me?"
At that moment, the normally black eyes of Uchiha Warai turned red as if bleeding, and three spinning tomoe appeared around their irises. A chakra pressure of an intensity and darkness Kannin had never fully been on the opposing end of started to engulf him.
'Oh shit!' Kannin thought
But before he was able to shake himself out of the grip of her Sharingan, he had already slumped over in his chair, the fork in his hand clattering to the tile floor. Warai stood up and kicked him hard in the leg before storming off, muttering with the faintest blush appearing on her cheeks
"'Mind showing me' that idiot..."
-
When Kannin woke up again, the quiche he was eating was now cold, and his leg hurt a lot. Warai was nowhere to be seen, but she had left a note saying she'd indeed help out with Kakashi, so at least that worked out.
'Maybe I joked a little too much' he thought to himself.
He wrote beneath her handwriting that he was sorry for going so far before heading out again. In the time he wasn't helping Kakashi or going out with Warai, he was training. Hypothetically he could be doing them all at the same time, but he had found after so many years of Shadow Clone training that, while it increased his rate of acquisition, it actually lowered the depth of his understanding a little. If he dedicated the entirety of his real mind to the problem he found he worked it out a lot more.
His work on Flying Thunder God was going to be slow, it seemed. All he could really do at this point was drill it everyday until his range increased and his mind acclimated to the strain of keeping track of all the formulas around.
Of course, there were the other two things, Senjutsu and his Kekkei Tota plan. The Kekkei Tota seemed totally out of reach. He had no idea where to even begin with it, how to blend the chakra natures, how to shape them, or what it would even look like in the end.
Senjutsu, on the other hand, Kannin knew how to do it, it was just difficult to do. First he needed to sense natural energy, and then he needed to draw it into his body and mix it with his physical and mental energies to create senjutsu chakra. Now that he thought about it, his original claim that it could double his chakra was wrong, it would only increase it by a third, but that was more than enough. If he played it right, and his chakra volume kept increasing as he aged, he'd be getting into tailed-beast levels of chakra with it.
Kannin was in a conundrum now. Sensing natural energy and using it generally required huge chakra reserves, so he couldn't split into shadow clones to speed up his process or else he'd risk not being able to do it at all, and Flying Raijin was so complex that he couldn't risk splitting for fear of not fully understanding it. This, of course, meant his progress was going to be much slower, which didn't excite Kannin.
For the next few days he worked on them both, with little progress in either. He could at least execute Flying Raijin, but it was nowhere near close enough for combat application. He had extended his range by five feet in that time, which was a pretty dismal pace if he wanted to be anywhere near Minato in a month's time. Senjutsu was going way worse. He had no idea what natural energy felt like, so every gust of wind, every sudden breeze could've been this magical 'natural energy' coursing through his veins. He sat absolutely still, or at least he thought he did, but every time he managed to clear his head and even dream about stillness, he'd think about the dozen other things he was trying to do, not least of which Warai, but also his mother, his job, Minato, Kakashi, the Nine-tails attack that was in the near future, and so much more. Peace of mind was hard to come by, even if the war was basically over.
Sighing, he packed up his things and headed back home. He wanted to get a good sleep since tomorrow he was meeting with Kakashi and Warai for Sharingan Day as he'd started calling it. But before he was 20 feet from the training area he had made for himself, a shinobi in a childish fox mask appeared in front of him.
"I thought I had managed to find an area away from prying eyes" Kannin said with some annoyance.
The voice of the Anbu in front of him rang out like a dull drone emanating from the depths of his belly, "Shimura Danzo would like to have a word with you."
'It's about time' Kannin thought.