Still unconvinced, Hoshiyomi once again poured that special Yin Release chakra into Shin's Mangekyō.
These Sharingan showed no signs of rejection. No matter how much chakra Hoshiyomi fed into them, they absorbed all of it—like a bottomless pit.
Watching Shin sit there with his eyes closed, looking as if he were enjoying it, Hoshiyomi felt his irritation rising. He stared at Shin suspiciously and asked:
"You just said you only needed one day to fully recover your own chakra. So why is it that I've already poured nearly half of my chakra into you, and you still don't look anywhere near full?"
Hearing this, Shin slowly opened his eyes and said innocently:
"It's been full for a while. But I suddenly realized that after the ocular power filled up, it could still grow slowly. So I didn't want to interrupt you, Lord Hoshiyomi."
Upon hearing that, Hoshiyomi's expression finally brightened a little. Being able to keep growing was good—it at least proved that the eyes he created weren't useless.
"So you're saying your eyes can keep absorbing endlessly?"
Shin shook his head lightly.
"Not exactly. Actually, even if you didn't ask, I would have soon requested that you stop the Yin Release infusion.
The ocular power in these eyes is already at my limit. I don't know what will happen if it exceeds that limit, but I'm certain the result will be even more miserable than before."
Seeing Shin so calm and rational, without any signs of arrogance, Hoshiyomi frowned again. He had discovered another difference between his artificial Mangekyō and a natural one.
In the original story, when Sasuke awakened the Mangekyō, he was bursting with arrogance. Even Kuugetsu, when awakening her chakra, behaved similarly. Though she acted modest in front of Hoshiyomi, she was cold and proud when speaking to others.
But Shin showed no disrespect at all when talking. His gaze remained clear, and his chakra didn't carry the coldness that Kuugetsu and Sasuke had.
Thinking of this, Hoshiyomi stopped the Yin Release chakra infusion and turned to Orochimaru:
"Give Shin a full-body examination first. Check whether there are any changes in his physical data."
After saying that, Hoshiyomi found a chair and sat down. Continuously infusing Yin Release for so long had exhausted even him, and he needed proper rest.
After nearly half an hour of meditation, Orochimaru finished Shin's physical examination.
Taking the report from Kabuto, Orochimaru skimmed through it and said with a strange expression:
"Hoshiyomi-kun, something feels off. Shin's body and chakra haven't changed much. His physical stats have improved compared to before the Sharingan transplant, but not by much.
I've seen Kuugetsu—after she awakened the Mangekyō, she was like a completely different person. Why is Shin's change so minimal? Is it because his talent isn't enough, or because he's not of the Uchiha clan?"
Hoshiyomi slowly shook his head.
"That's probably not the reason. I think it still comes down to this: Shin's Mangekyō was artificially created. Without undergoing that mental transformation, the results are bound to be different.
Let's keep observing for now. We'll decide after watching Shin's progress over time."
...
For the next half year, Hoshiyomi's routine remained the same: mornings at home teaching his children and playing with them, afternoons in Orochimaru's lab, studying Shin's changes together.
Through long-term observation, they finally understood the various strengths and weaknesses of the artificial Sharingan.
The artificial Mangekyō that Hoshiyomi and the others created still differed greatly from the Mangekyō awakened by the Uchiha through emotional metamorphosis.
Let's start with the advantages.
The most obvious advantage of the artificial Mangekyō Sharingan is that it does not cause blindness.
Because its ocular power is produced through the combination of Hashirama cells and special Yin-Release chakra, this power does not place pressure on the optic nerves. It won't cause the eyes to bleed or the user's vision to deteriorate from excessive use.
Even if Shin uses his Mangekyō abilities multiple times, he only becomes weak—similar to chakra exhaustion—but he won't suffer blurred vision like Kuugetsu or Sasuke.
Another advantage is that this artificially created Sharingan is more balanced, gentle, and easier to control.
The ocular power of an artificial Mangekyō doesn't suddenly skyrocket like a normal Mangekyō. Instead, as the user's physical condition and chakra increase, the upper limit of ocular power grows steadily and smoothly.
This stable growth makes the artificial Mangekyō much easier to handle, preventing situations like Sasuke's loss of self-control caused by a sudden surge of ocular power.
At the same time, the increase in ocular power subtly nourishes the body, steadily boosting Shin's strength.
When he first awakened the Mangekyō, Shin's strength wasn't much different from before. But now, his power has already reached the semi-Kage level—a considerable improvement.
Now for the disadvantages::
The first and foremost issue is that the artificial Sharingan does not undergo the emotional metamorphosis of gaining and losing love. Because of this, its ceiling is extremely limited.
Even if it is elevated to the level of the Eternal Mangekyō with the help of special Yin-Release chakra, it will still be weaker than a naturally awakened Eternal Mangekyō.
Another drawback is that when these eyes first awaken, their "energy bar" is extremely short. Because there was no emotional transformation, the user has no ocular power available at the moment of awakening.
The ocular power restored through Hashirama cells and the user's chakra is very limited—only enough for about three to five uses.
Although ocular power will naturally increase once the reserve is full, the speed is embarrassingly slow. Hoshiyomi estimates that if Shin were left to grow on his own, it would take 20 to 30 years for him to reach the level of Kuugetsu and the others when they awakened their Mangekyō.
So compared to a normal Mangekyō, it's hard to say which one is actually better.
Both have strengths and weaknesses.
The artificial Mangekyō is calmer, gentler, and easier to control—but at the cost of some potential and raw power.
A natural Mangekyō is fierce and explosive, allowing a massive leap in ability, but it also easily causes the user to lose themselves in its power and eventually go blind.
In Hoshiyomi's view, the artificial Mangekyō experiment is extremely successful and highly meaningful.
After all, in this life, the Uchiha clan will not be exterminated. That means if Obito and others still want Mangekyō abilities, they will have to choose the artificial Mangekyō path.
There's another key point: although the evolution from three-tomoe to Mangekyō is restricted in this way, the upgrade from Mangekyō to Eternal Mangekyō is not.
Using special Yin-Release chakra to elevate a Mangekyō to the Eternal Mangekyō will not weaken its power.
Hoshiyomi finally has a way to help Kuugetsu obtain the Eternal Mangekyō.