Along with Rei's progress in seals, and his own improvement, he did get to find out two things.
One, Kakashi was a year younger than him, aka he was there to see when he was born, or at least celebrate his 'Birth'day. Which started a mental dilemma if he wanted to somehow prevent Kakashi's dad's death, or just let it happen. It wasn't really Kakashi without his hidden daddy issues, right?
He also got to finally meet Mei, which by no surprise was energetic as hell, but still reserved in a, strangely matured way? It was much easier for Rei to be around her as such, his own clan the Talmos, were close friends to the Terumi clan. Whereas Talmos were known for their ability for information gathering, scouting, and sneaking, the Terumi were known for their chakra and ninjutsu prowess. The story behind how they got here was during a particularly tense time where they used to be, they moved to Konoha, and after a contract they were allowed, which now accepted them with kind arms since they've been around for almost 80 something years, from the founding of the village, they still weren't considered a large clan when compared to the Uchiha or Hyuga, but they were strong because of their rare blood limit.
So, Rei spent time with Mei, dealing with her constant wish to build her own hidden fort, he didn't know if this was a cannon thing that just wasn't discussed, but Rei didn't mind. It could be seen as a reason as to why he has a secret underground bunker in the future, but that's for future Rei to worry about.
Along with learning chakra theory and the knowledge over things without actually learning how to use chakra yet, despite already knowing how he strictly followed his parent's orders to not use it until he was at least three. What he did, however, was focus on building his ability to hold chakra as well as how fast he could replenish it., basically cultivating. No matter what he thought to call it, it was what he was doing.
He couldn't increase his initial reserves as of now without straining his body, instead, he focused on how he could house it, either the extra chakra in his chakra points, or how fast he could draw chakra back, it was actually during one of these meditative sessions with rip and tear playing in his ears that he got a notification from the system.
Apparently, his chakra as a whole, including the chakra points, the veins, and everything about them has been added to the list of things he could evolve with time.
It was also a good time to mention a few things Rei has learned about his ability to 'Evolve.'
He could evolve, literally anything about himself with enough time and training. Down to how dense and strong his toenails were if he wanted. Each thing brought its own change, or benefit. Sometimes it even brought what could be considered a penalty, but it wasn't much. Simple things like, stronger, denser muscles would of course be heavier than normal.
The stronger his nails, the hard it would be to clip them, small things like that, but when he thought about being able to control how long his nails were and be able to rip pieces of rock out of a mountain, it seemed a small price to pay, after all. Who doesn't want to be a literal walking weapon in this day and age?
There were also small milestones that could be reached that increased the small aspects, he thought it was around the 25% mark they hit a milestone, but some things didn't do the same thing, at least he didn't notice the small improvements right away.
The core aspects of his body had risen to a decent percentage, his organs, muscles, skins, tissue, all the deep bits had risen to a base percentage of all being around 11% to 12% into the first evolution, however, things that we're much further ahead were his eyes, mind, awareness, and motor skills. He noticed that even his chakra was quite far ahead, and it seemed there was definitely a passive increase of his abilities due to chakra, it was minor, but it was still good.
Some of the small milestones, including the one of him being able to practically see inside himself, or at least feel it. Included improvements to his reflexes, his eyesight, and even how much he could breathe in. Maybe he should think about making a breathing style for himself, and or, a style of breathing that helped benefit him for the weapons he decided to use, or the style of martial arts he used. He wanted to punch things to death, but practicing martial arts would help improve the overall control and ability of his body as a whole.
He planned to become the living embodiment of a 'Living Weapon.' and to further set in stone how true it is to always have a great body.
Maybe he'd open a dojo in the future-focused around some shit like ''No matter the weapon, always train the body to be your greatest weapon.''
That, or, he could just monopolize on it all himself and become a god to these mortals?!
He roared into childish laughter and giggles, hands on his waist and his head thrown back, which his Mother could very well see since he was in the backyard in view of the window of the kitchen, and others could hear it.
Of course, she had no idea why he was laughing, but she decided right then and there, even if her son was a genius, and ended up a bit weird, she'd love him all the same.
Rei? Completely oblivious to the fact his inside joke turned into a strange misunderstanding.
(Pa-treon.)