Cautious Eyes: An Uchiha's Path

The experiment had begun—naturally, the sooner, the better.

If it weren't for the uncertainty surrounding the Hyūga clan's willingness to release her, Uchiha Akiha might have initiated the operation himself. Though the fusion period for the Eternal Mangekyō Sharingan could be lengthy, Uchiha Kai didn't want to waste any time.

Soon after completing their mission, Uchiha Kai, Imai Kenta, and Uchiha Gawa handed in their reports. Then, Kai personally escorted Hyūga Aya to the underground laboratory.

The lab was more sparsely staffed than before. With additional shinobi being dispatched to support Kakashi's front, some personnel had been drawn away. Even so, the perimeter defenses remained comprehensive. Uchiha Kai and Uchiha Fugaku had ensured that no unauthorized individuals could approach this hidden and highly confidential site.

Upon entering, Kai led Aya directly to the secured chamber where Uchiha Osamu and Uchiha Yugi were kept.

The brothers still floated inside their respective life-support pods, immersed in nutrient-rich fluid. They appeared asleep, though in truth, their states were far more complicated.

Once the pods were powered down, Kai and Aya lifted them out and placed the brothers on adjacent beds. Aya immediately began attaching various life-monitoring devices to Osamu.

After confirming stable vital signs, she asked, "Do you want me to remove Yugi's eyes now?"

Kai nodded. "Yes. Be careful not to damage the eyes. Once the removal is complete... end him."

Uchiha Yugi's body had long been studied and cataloged. Though his physical form was still alive, his consciousness had been completely erased—a husk, kept alive solely for its ocular power.

Kai had kept his promise. He hadn't gone after Yugi's lover, nor targeted his remaining family—aside from Osamu. In Kai's mind, he had shown all the mercy one could ask for. If any part of Yugi's soul remained trapped in that body, then death would be a release.

His brother would be joining him soon anyway.

Aya said nothing, simply lowering her head in silent understanding. A green chakra glow formed over her palm as she pressed her hand gently to Yugi's eye socket. For a skilled medical-nin like Aya, the extraction of ocular tissue was a straightforward task.

In less than five minutes, she had removed both of Yugi's Mangekyō Sharingan, placing them carefully into a storage medium lined with preservation seals.

Despite no longer being active, the eyes retained a dreadful aura—twisting patterns that threatened to draw the viewer inward. Aya frowned, instinctively uneasy.

"These… they feel wrong," she murmured. "Like they're still watching us."

Kai's gaze never left the Sharingan. "That's what power looks like when it outlasts the person who forged it."

Aya exhaled and, without fanfare, pressed her chakra-coated fingers against Yugi's carotid artery. A soft pause. Then silence.

Kai didn't glance at the body. His focus remained on the eyes. But something troubled him.

The fusion of the Eternal Mangekyō Sharingan involved the dominant eye absorbing the chakra and power of the other. But would that also preserve the original abilities? He wasn't sure.

Sasuke, after transplanting Itachi's eyes, retained Amaterasu—perhaps due to a transcription seal Itachi had implanted in advance. But techniques like Tsukuyomi, unique to Itachi, seemed to be lost.

"Maybe it depends on whether the abilities were sealed, or just innately embedded in the eyes," Kai muttered. "Or maybe the fusion process simply overwrites incompatible chakra signatures."

In any case, the eyes would not remain Kai's. Once fused, their abilities might not survive. That was acceptable—especially if Yugi's Susanoo-enhancing ability didn't mesh well with Kai's own chakra nature.

The Mangekyō he wielded had already progressed to a stabilized second stage Susanoo. Even in his three-tomoe Sharingan state, he could partially manifest the first stage—though with difficulty. For now, it was enough.

He dismissed the thought. Yugi's power had been interesting: his Mangekyō technique, called Hi no Mikoto—or "Flame Deity"—was a variation on Amaterasu. Unlike Kagutsuchi, which shaped and controlled the black flames, Yugi's ability amplified their destructive force. A terrifying enhancement when paired with base Amaterasu.

"If Amaterasu burned a forest," Kai thought, "Hi no Mikoto could burn a mountain."

That ability, paired with a powerful Susanoo, had once made Yugi a feared name within the Uchiha. But all that remained now were eyes—and death.

Let Fugaku handle the flames if he wanted. Kai had other plans.

He turned to Aya. "The next phase is the transplant. This will be difficult. Are you ready?"

Aya hesitated only a moment. "I'll try my best. I've only done full Mangekyō fusion once, and it barely succeeded."

"I'm aware. You're not expected to master it—just not to fail." Kai activated his own Sharingan. "I'll assist. I've studied our clan's ocular surgery techniques, but I don't dare perform this alone."

Aya gave a small nod and moved toward Osamu with the two harvested eyes.

Kai had once considered using the Transcription Seal technique to preserve Yugi's ocular powers and implant them gradually—but the clan's archives had warned against it. The seal disrupted natural fusion. Worse, once removed, the sudden release of chakra could cause the implanted eye to rupture.

Even for blood relatives, compatibility wasn't guaranteed. The Eternal Mangekyō required a delicate balance of chakra resonance and spiritual synchronization.

That was another reason why Fugaku hadn't attempted a transplant himself. Even if he could take Kai's eyes, their chakra natures didn't match. His Mangekyō would remain unstable, incomplete.

"Changing eyes won't fix anything," Kai thought. "The power is in the eyes—but the eyes are only as strong as the soul behind them."

If it were that simple, Madara and Izuna would have gained the Eternal Mangekyō decades earlier, and wiped out Hashirama without incident.

Or Itachi and Sasuke could have traded eyes the moment Sasuke awakened his Mangekyō, avoiding blindness altogether.

But Itachi had been fated to die. His sins had condemned him—his guilt, his burden. That hadn't changed.

As for Itachi now… Kai hadn't seen him since their last cryptic conversation. Fugaku hadn't brought him up either, and Kai didn't care to ask.

So long as he stayed out of the way, Itachi could live or die in peace.

Kai had other problems to solve—and they started with these eyes.