After leaving Karin's apartment, Uchiha Shinji found a secluded spot, where he quickly swapped out his Akatsuki cloak with the red clouds and mask. Then, under the guise of jogging around the village, he discreetly slipped into the Forest of Death.
Upon arriving at the familiar cave, he carefully inspected the interior, making sure no one else had been there. Once satisfied, he eagerly took out the nutrient tank containing his grandmother Uchiha Naori's Mangekyō Sharingan.
He stared at the eyes floating in the nutrient solution and whispered, "I've finally reached this day!"
To obtain the Eternal Mangekyō Sharingan, Shinji had gone through many trials, even risking his life by infiltrating Danzo's Root base.
But now, after all the hardship and danger, everything was finally paying off.
Swallowing hard, Shinji calmed his mind. He removed his grandmother Uchiha Naori's Mangekyō from the nutrient tank and held it in his palm.
Next, he activated Susanoo and Susanoo Tomoshibi to carefully remove the Mangekyō Sharingan of Uchiha Fugaku he had been using, replacing them with his grandmother's eyes.
At that moment, a sense of familiarity and closeness surged within him.
This was the bond of shared blood!
When fusing Mangekyō Sharingan from close relatives, there was no need to worry about strength, weakness, or even rejection of the dojutsu powers.
Steadying his mind, Shinji channeled his dojutsu power, attempting to activate the left eye that had been restored to sight by Karin.
As the Mangekyō's power flooded into the once-blind left eye, it gradually turned scarlet, three tomoe appeared, then merged together, forming a petal-like pattern.
"Success!"
Shinji felt a surge of elation and, at the same time, information flooded into his mind.
It took him a moment to process before he muttered to himself, "No wonder Grandmother chose to sacrifice her left eye... Wazunagi's ability is like this..."
Upon activating the once-blind left eye, the details of Wazunagi's power immediately entered his mind.
It turned out that Wazunagi was an ability that depended on Jikibi.
Jikibi established a connection between individuals, while Wazunagi took it a step further—it could drain the chakra of everyone linked through Jikibi.
In other words...
If Shinji were to activate Wazunagi now, he could remotely extract the chakra of anyone within Jikibi's sensing range—like Haku or Karin—into his own body!
"One transmits information, the other transfers energy. Together, these two eyes..."
For a moment, Shinji struggled to find the words.
Just imagine: if Shinji used Jikibi to link seven people, during battle, his chakra reserves would be equivalent to the combined total of 1+7 individuals.
And if one of those linked was a Jinchūriki with vast reserves of chakra, his own chakra supply would be nearly limitless.
Of course, there would be significant chakra loss during the remote extraction.
But even so, the combination of Jikibi and Wazunagi was terrifyingly powerful!
Shinji sighed, "If Grandmother hadn't sacrificed her left eye, perhaps she could've led the Uchiha clan down a different path."
Without Jikibi, Wazunagi would be like a rootless weed.
And without Wazunagi, Jikibi was little more than a messaging tool.
Only when the two were combined could their powers fully synergize, creating an unimaginable force!
Fortunately, Shinji had now restored Wazunagi and could once again pair it with Jikibi.
Putting the matter of the dojutsu aside for the moment, Shinji turned his attention to the main event of the night.
No matter how great the dojutsu, they required powerful eye strength to sustain. The foundation of it all was the Eternal Mangekyō Sharingan.
Shinji had a strong feeling!
Once he used Susanoo Tomoshibi to fuse his own Mangekyō with his grandmother's, not only would Susanoo Tomoshibi become more potent, but the powers of Jikibi and Wazunagi might also receive a corresponding boost!
And so, he activated Susanoo Tomoshibi once again and began the fusion process.
Suddenly.
The two sets of eyes in his Susanoo began to merge!
Roar!
A loud roar echoed from his colossal Susanoo, reverberating throughout the cave.
The sound shook the walls, causing rocks and debris to fall from the surrounding cliffs!
Out of nowhere, Shinji felt a wave of dizziness.
Suddenly, everything went dark—he couldn't see anything!
But he didn't panic. He could still feel his Susanoo, and as long as it remained, his eyes were fine. This blindness was only temporary.
However, as time passed, the growing inability to see did cause him to feel a hint of unease.
After what seemed like an eternity, light finally reappeared before his eyes.
He blinked several times, and when his vision cleared, he saw the yellow form of his Susanoo, along with the dim cave around him.
"It worked...?"
Shinji was both anxious and excited.
He quickly retrieved a mirror he had prepared earlier and positioned it to examine himself.
Looking closely, he saw that his Susanoo's second set of eyes had gone empty, but in the first set, two pairs of eyes were now merged together.
This bizarre "double pupil" had an eerie and inexplicable look to it!
"It seems that even using Susanoo Tomoshibi, fusing two sets of Mangekyō Sharingan still takes time."
Sighing in amazement, Shinji glanced at his own eyes.
They appeared to still display the normal Mangekyō pattern, without the strange double-pupil effect seen in his Susanoo's eyes.
This clearly indicated that the fusion was happening within his Susanoo and wouldn't affect his actual body.
He decided to try deactivating his Susanoo. Sure enough, even after doing so, he still felt the fusion process continuing within his body.
"Heh, this is incredibly convenient!"
Shinji smiled.
There was no need for surgery or rest. The fusion of the two Mangekyō Sharingan was happening quietly and seamlessly!
After packing up his belongings, Shinji prepared to leave the cave.
But just as he reached the cave's entrance, a sudden burst of sensation surged through his eyes. Moments later, an intense amount of Yin Release chakra exploded from within him, so dense it was almost visible to the naked eye.
It took several moments for the turmoil in his eyes to settle down.
And as the discomfort faded, he realized that his dojutsu power had increased dramatically!
He was both surprised and overjoyed.
The joy came from the unexpected boost in his dojutsu power. If this continued to happen, the level of his eye power might reach unimaginable heights.
But the surprise came from the fact that this surge had occurred without warning. If there had been someone nearby, his Mangekyō Sharingan would have been exposed.