As a nascent lifeform, the "biological exoskeleton" possessed formidable chakra and a pair of enhanced pure Byakugan. However, it had no training against illusions and likely didn't even understand what they were. Thus, it succumbed to Shinji's illusion with almost no resistance.
Within the illusion, Shinji began shaping the exoskeleton's worldview, instilling a sense of loyalty to him and the Akatsuki, and fostering its acceptance of coexisting with Neji to strive for the ninja world's salvation.
Moments later, Shinji exited the illusion state.
The gleam in his Eternal Mangekyo Sharingan dimmed slightly, a clear sign of overexerted dojutsu power.
Even with the Eternal Mangekyo, casting illusions wasn't without limits.
The only illusions capable of freely manipulating time, space, and substance were Tsukuyomi, and the only one that could freely alter a target's will was Kotoamatsukami.
Shinji possessed neither, so he relied on raw dojutsu power, which was less efficient and consumed vast amounts of energy.
Still, seeing the "biological exoskeleton" become docile—relinquishing its struggle for Neji's body and even suppressing its instinct to commune with the giant Tenseigan—Shinji felt the expended dojutsu power was worthwhile.
"My lord!"
Neji's face, still tinged with fear, finally lit up with joy.
Shinji said, "From now on, you two need to work together!"
Neji nodded instinctively.
The speechless "biological exoskeleton" wiggled its implanted enhanced Byakugan up and down, signaling compliance with Shinji's command.
Neji, looking down at the scene, felt an indescribable eeriness.
Ignoring Neji's unease, Shinji pondered briefly before addressing the exoskeleton. "From now on, you're a member of our Akatsuki. Your codename is 'H'!"
The exoskeleton, now 'H,' heard Shinji's words through Neji's senses and was thrilled, its enhanced Byakugan gleaming with delight.
Once 'H' reverted to its dormant state, concealed beneath Neji's skin, Shinji gave Neji a few more instructions and sent him off.
By now, the sky was beginning to lighten.
Shinji let out a long breath and quietly returned to his apartment.
After a quick wash, too restless to sleep, he dressed and headed to the Shinobi Academy at dawn, as usual.
The academy's morning training field had become the liveliest spot in the Hidden Leaf.
As Shinji expected, Neji, equally unrested, dragged his weary body to the academy and began training on the field.
In another corner, Kimimaro, who had arrived earlier, was already deep in practice.
Shinji discreetly observed them, reassessing his Tenseigan Plan.
In his original plan, the "biological exoskeleton" served as a mediator, with either Neji or Kimimaro ultimately achieving the Tenseigan.
Now that the exoskeleton had gained sentience and become 'H,' the task of attaining the Tenseigan could be entrusted directly to it.
This was why Shinji had implanted the enhanced Byakugan into 'H.'
If any Byakugan in the ninja world was best suited for evolving into a Tenseigan, it was likely the pair in 'H.' Shinji estimated that if Neji and Kimimaro continued storing chakra as planned, 'H' could initiate the fused state, drawing on Neji's Byakugan chakra and Kimimaro's Shikotsumyaku chakra.
These two chakra sources, derived from Hamura Otsutsuki's lineage, combined with an ultra-pure Byakugan and the authority to commune with the giant Tenseigan, meant that 'H,' Neji, and Kimimaro together met nearly all conditions for achieving the Tenseigan. The only missing piece was chakra accumulation.
Withdrawing his gaze, Shinji mused, "At this rate, the Tenseigan might beat the Samsara Eye to the finish line!"
He then cautioned himself to steer clear of the Otsutsuki branch family on the Moon for a while.
Having fused his two Byakugan into one enhanced pair for 'H,' he no longer possessed any Byakugan. Without Byakugan chakra to counter the giant Tenseigan's chakra absorption, encountering the Otsutsuki now could result in his chakra being drained instantly, leading to a swift defeat.
Another inconvenience was the loss of his x-ray vision without a Byakugan.
"It's going to take some getting used to!"
Muttering to himself, Shinji mentally cataloged his collection of dojutsu Bloodline Limits.
The fully and partially damaged Mangekyo Sharingan he'd retrieved from Danzo's Root base had mostly been used to fuse Eternal Mangekyo Sharingan.
Currently, he controlled two pairs of Eternal Mangekyo Sharingan: his own and the pair in Karin's sockets.
The only remaining Mangekyo Sharingan was Uchiha Fugaku's, containing the dojutsu Amaterasu and Izanami no Mikoto.
Additionally, he had one pair of worn, heavily depleted three-tomoe Sharingan from the same Root batch.
Later, he fused two pairs of Hogan into an enhanced Hogan.
From Hell Valley, he collected eight pairs of Blood Dragon Eyes. Due to a minor error during fusion, five pairs were consumed to create one pair of Super Blood Dragon Eyes.
He then fused the enhanced Hogan and Super Blood Dragon Eyes into the Koryugan now in Yakumo's sockets.
In summary, excluding Karin's Eternal Mangekyo Sharingan, Yakumo's Koryugan, and 'H's enhanced Byakugan, Shinji had six pairs of eyes left:
His own Eternal Mangekyo Sharingan, Uchiha Fugaku's Mangekyo Sharingan, three pairs of Blood Dragon Eyes from the Hell Valley batch, and the worn three-tomoe Sharingan.
Blood Dragon Eyes were illusion-based and lacked x-ray vision, so even though Shinji integrated a pair via Susanoo Tomoshibi, he still couldn't see through objects.