Naruto: Blade of the Sharingan

"Gyomei Himejima-san, thank you for this month of training. You've made me considerably stronger." Uchiha Nagi bowed deeply to the man, his gratitude genuine. He had initially planned to train for half a month, but it ended up stretching to a full month because Himejima's training was simply too effective.

Among the nine Hashira, Gyomei Himejima might not have been the fastest, nor his attacks the sharpest, but his physical body was undoubtedly tempered to the absolute extreme. A giant standing at 2.2 meters, wielding a flail and axe, he'd roar "Namu Amida Butsu" and crash down on his target, the very image of a Wrathful Vajra.

Alas, he had no wrathful eyes, for he was blind. But this was precisely what Uchiha Nagi admired most: a man blind in both eyes whose strength had soared to the Hashira level. In the later stages, even Muzan would lament that Gyomei Himejima's physique was the most formidable he had encountered in centuries. He couldn't see, yet he could sense his surroundings, using all his body's senses except sight to assess the situation. If one didn't look at his eyes, one would never guess he was blind.

"The Buddha is merciful. With every bit of strength humanity gains, the possibility of Muzan's eradication increases. Uchiha-san, there is no need for thanks," Gyomei Himejima said, tears streaming down his face as he pressed his palms together. "Speaking of which, it is Uchiha-san who has astonished me. Your body's ability to endure such intense training, your battle aura growing stronger day by day—it is truly a blessing for the Demon Slayer Corps."

During the muscle enhancement training, Uchiha Nagi had given Gyomei Himejima too many surprises. Possessing White Zetsu cells, Nagi's physical recovery was astonishingly rapid. Moreover, the high-intensity training unlocked his body's potential, allowing the White Zetsu cells to fully exert their effects, causing Uchiha Nagi's Chakra to increase daily. Thus, in Himejima's perception, the battle aura within Uchiha Nagi's body grew stronger with each passing day.

Little did he know, Uchiha Nagi had been constantly analyzing and copying his abilities with his Sharingan.

[To see through and analyze the operational principles of things.]

The essence of this eye's ability lay in these two aspects: seeing through and analyzing. Uchiha Nagi spent an entire month analyzing Gyomei Himejima's perceptual ability, which was just half a step away from the Transparent World. This kind of ability, like the Transparent World itself, wasn't a skill that could be copied simply by seeing through it. So, Uchiha Nagi could only analyze it repeatedly.

Finally, with Gyomei Himejima's help, he attempted to forsake his strongest asset, the Sharingan's dynamic vision. He blindfolded himself with a strip of cloth and underwent special training. Through relentless effort, he successfully mastered the ability to fight with his eyes closed.

Uchiha Nagi couldn't help but think of Madara. After his resurrection, when his Rinnegan from Edo Tensei shattered, Madara fought a host of enemies with his eyes closed without any pressure. Had he too reached a state similar to the Transparent World? So, Madara didn't actually need the Mangekyo's dynamic vision in battle; the Rinnegan was merely for its special abilities. Disregarding the Rinnegan's powers, Madara's strength was virtually unchanged whether his eyes were open or closed. Even without eyes, his Susanoo could be activated; even if he couldn't see his enemies, he could still fight. He could even effortlessly dodge a surprise attack from the Flying Thunder God technique.

This made Uchiha Nagi greatly covet the power of the Transparent World, a state and ability akin to the Taoist Heavenly Eye or the Buddhist Mind's Eye. The Transparent World had different names in different worlds—the Taoist Heavenly Eye, the Buddhist Mind's Eye—but upon careful analysis, they were all very similar: a way of perceiving the world with one's heart.

Gyomei Himejima had practiced Buddhist dharma for many years and was blind, which was why he possessed this ability. However, he was still one step away from the Transparent World. Nagi estimated that only a truly cathartic life-and-death battle would allow him to cross that final step.

"Gyomei Himejima-san, please give this to Ubuyashiki-san. It's something I've researched, containing production materials and an introduction. I believe it will be of great help to the Demon Slayer Corps." Uchiha Nagi handed him a scroll. This scroll would release its contents upon being opened, requiring no Chakra input.

"Will it help the Demon Slayer Corps? That's wonderful! Namu Amida Butsu. May I ask what is inside?" Gyomei Himejima inquired.

"Nothing much, just a type of ultraviolet lamp," Uchiha Nagi said with a smile, then proceeded to explain it to Gyomei.

After capturing the bald ramen shop owner and other demons, Uchiha Nagi had been relentlessly studying these vampire-like creatures. Garlic, crucifixes, ultraviolet light, silver—he had tried them all. He finally discovered that ultraviolet light was effective against them, but not enough to kill them.

The technology of this world was comparable to the period around World War I; ultraviolet light had not yet been invented. But Uchiha Nagi was different; he was a transmigrator. He knew that sunlight contained ultraviolet rays. So, through a series of studies, he developed UV lamps and experimented on his captured subjects. He found that UV light burned them like fire. It was useful, but it couldn't kill them. Uchiha Nagi was also helpless in this regard; sunlight contained many things besides just ultraviolet rays.

Still, it was enough. If Demon Slayer Corps members below the Kinoe rank were equipped with UV lamps, then any demon below the rank of the Twelve Kizuki would be in for a tough time. Before a fight even began, a barrage of UV lamps shining like lasers could weaken them. Then, during the battle, if a few teammates continuously shone flashlights on the demon, it would be like having a host of support.

Thinking about how the bullets Genya Shinazugawa used in his firearm were made of sun ore, Uchiha Nagi wondered what would happen if he created hand grenades filled with small steel pellets made of the same material as Nichirin Blades...

After listening to Uchiha Nagi's explanation, Gyomei Himejima was moved to tears again. He clutched the scroll excitedly; this invention was practically a godsend for the lower-ranked members. The thought that so many lower-ranked members wouldn't have to be sacrificed each year made Gyomei incredibly happy.

"Uchiha-san, you must have been sent by the Buddha to end Muzan! I have a premonition that Muzan will be completely annihilated by our generation of Hashira."

"Hehe, you're too kind. Well, I shall take my leave then. By the way, I have one more thing to entrust to you," Uchiha Nagi said.

"Please speak—"

"Could I trouble you to tell Ubuyashiki-san to help search for the grave of the founder of Sun Breathing, Yoriichi Tsugikuni? If it can be found, I might have a way to end Muzan when I return—"

With that, Uchiha Nagi vanished from Gyomei Himejima's bewildered senses. He used the Body Flicker Technique to leave, stopping after covering some distance.

" Let's begin. With nearly six or seven units of Chakra this time, I probably won't deplete my Chakra and pass out," Uchiha Nagi muttered to himself.

Then, with a whoosh, he silently disappeared from this world.