After deciding to heavily invest in Yachihoko, Shinji took out Uchiha Fugaku's pair of Mangekyo Sharingan.
Within this pair of Mangekyo Sharingan dwelled the two powerful Mangekyo dojutsu: Amaterasu and Izanami no Mikoto.
Especially Izanami no Mikoto, a dojutsu tied to fate, was, to some extent, far more precious than ordinary Mangekyo dojutsu.
Staring at the pair of Mangekyo in the small nutrient tank, Shinji's fingers lightly tapped the desk.
Tap tap
To fuse a pair of Eternal Mangekyo Sharingan, simply gathering two pairs of Mangekyo Sharingan wasn't enough to easily accomplish the task.
This process also involved whether the bloodlines were connected, meaning whether the chakra natures of the two pairs of Mangekyo were similar.
Without a bloodline connection, the success rate of fusion would be greatly reduced.
However, Shinji had already found a way to bypass this restriction—by replicating Karin's method of fusing Eternal Mangekyo Sharingan!
The method was simple.
Deplete the Mangekyo Sharingan to be fused to its absolute limit, rendering it completely blind, even to the point of chakra exhaustion, entering a half-damaged state.
Then, through the fuser's chakra, nurture and revive this half-damaged pair of Mangekyo Sharingan, bringing it 'back from the dead'!
This way, the 'revived' pair of Mangekyo Sharingan would share a kind of bloodline connection with the fuser, or rather, their chakra natures would be extremely close, thus meeting the conditions to merge into a single pair of Eternal Mangekyo Sharingan.
Though crude, this method had been proven feasible through practice. As long as Shinji was willing to use Uchiha Fugaku's pair of Mangekyo Sharingan and perform the necessary steps, he could fuse a pair of Eternal Mangekyo Sharingan for Mumei.
…
A few days later.
In the secret laboratory, Shinji opened the nutrient pod where Mumei was sleeping.
Mumei opened her eyes and stretched lazily with a long yawn. "So comfortable! It's been ages since I slept this well!"
Yawn
Shinji smiled and began recording data.
Mumei leaned over, asking with familiarity, "How's my body data this time?"
While jotting down the numbers, Shinji replied, "Your recovery is excellent, even surpassing my expectations!"
Mumei's eyes lit up with surprise. "Really?"
Shinji nodded lightly. "It's likely due to Yachihoko. Over the years you were sealed, it continuously absorbed chakra from people and creatures that wandered into the forest, replenishing you. That's why your body hasn't deteriorated despite the deficit!"
If Mumei's body had decayed completely, like the middle-aged shinobi at another sealing point, not even Shinji's medical ninjutsu or extensive knowledge of pharmacology could have saved her.
Mumei asked, "Can I use my Sharingan now?"
Shinji pondered for a moment before answering, "Your own dojutsu, Yachihoko, can be used freely now. However, the Amaterasu and Tsukuyomi implanted into your body through a technique—I'm not yet certain of their condition. It's best not to use them lightly."
"Why not?"
Shinji explained, "It's not just a matter of chakra. It also involves the original owner's mental energy tied to Amaterasu and Tsukuyomi. Until your chakra level can fully suppress theirs, each use of Amaterasu or Tsukuyomi risks contamination by their mental energy."
Mumei nodded, half-understanding. "I'll listen to you and avoid using Amaterasu or Tsukuyomi."
"Come with me!"
With that, Shinji turned and headed toward the underground training ground nearby.
Mumei followed curiously. "Are we going to the training ground?"
Leading Mumei to the underground training ground, Shinji casually tossed her the small nutrient tank containing Uchiha Fugaku's Mangekyo Sharingan.
Mumei hurriedly caught the tank, her attention immediately drawn to the pair of Mangekyo Sharingan floating inside. "Shinji, what are these?"
Shinji said, "This is a pair of Mangekyo Sharingan containing the dojutsu Amaterasu and Izanami no Mikoto!"
Mumei's eyes widened. "Shinji, you actually have another pair of Mangekyo Sharingan?"
"It's no big deal!" Shinji waved dismissively. "If you want to possess a pair of Eternal Mangekyo Sharingan, you'll need to fuse with these!"
Mumei didn't immediately agree with excitement. Instead, she looked at Shinji. "This pair of Mangekyo Sharingan must be very useful to you, right? If I fuse with them, will it affect you?"
Shinji shook his head. "It's fine!"
Mumei let out a relieved breath. "Alright then, what do I need to do?"
"Normally, fusion requires two pairs of Mangekyo Sharingan connected by bloodline! But I've found a way to bypass this restriction, so just follow my instructions!"
With that, Shinji guided Mumei to activate Susanoo Tomoshibi.
Indeed, because Susanoo Tomoshibi was recorded in the gemstone shared between her and Shinji, Mumei could activate Susanoo Tomoshibi by using Yachihoko.
Of course.
Since Mumei herself was only at the Mangekyo Sharingan level, the Susanoo Tomoshibi she activated was also at the Mangekyo level, capable of wielding only one additional pair of eyes beyond her own Mangekyo Sharingan.
Following Shinji's guidance, Mumei quickly activated Susanoo and Susanoo Tomoshibi. In an instant, a red Susanoo towered within the underground training ground.
Whoosh
Shinji said, "Now try wielding this pair of Mangekyo Sharingan!"
Having activated Susanoo Tomoshibi, Mumei had already grasped its basic abilities. She easily used Susanoo Tomoshibi to wield Uchiha Fugaku's pair of Mangekyo Sharingan.
Wielding them was only the first step.
Shinji said, "Get familiar with it first!"
After sensing the wielded state, Mumei's face lit up with joy. "Shinji, I feel my dojutsu power has grown so much stronger!"
Shinji nodded. "Thanks to Yachihoko, your Mangekyo has always been at its peak. So, even though both are Mangekyo Sharingan, the strength difference between the two pairs is clear, and the boost in dojutsu power from wielding them is significant!"
After adapting for a moment, Mumei marveled, "Shinji, this dojutsu of yours is amazing!"
Though Susanoo Tomoshibi's wielding came with various restrictions, it undeniably enhanced dojutsu power, so Mumei's amazement was heartfelt.
Shinji asked, "You should be able to use the dojutsu of the other pair of Mangekyo Sharingan now, right?"
"Mm-hmm!"
Mumei nodded repeatedly.
Shinji then said, word by word, "Now, I need you to completely exhaust the dojutsu power of the other pair of Mangekyo Sharingan. Leave nothing behind—make it fully depleted, completely blind!"
Mumei froze. "Huh?"