The Uchiha's Sharingan is, in essence, the physical manifestation of Yin Release. Under the influence of intense emotional stimuli, it undergoes radical transformations.
While the eye Menma had swiped from Orochimaru was merely a two-tomoe, he combined his own research into Bloodline Limits from the "Limited Tsukuyomi" world with concentrated Yin Release chakra. As expected, he forced the eye to evolve into a full three-tomoe Sharingan.
Though it couldn't yet hold a candle to the Mangekyō, this eye granted Menma access to a vast array of unique genjutsu—and even the forbidden Izanagi.
As for the heightened kinetic perception—the ability to see an enemy's movements in slow motion—it was actually the least significant upgrade for someone of Menma's caliber, whose strength already eclipsed that of an average Kage.
After successfully transplanting the eye and forcing its evolution, Menma enjoyed a satisfied, restful sleep.
Early the next morning, he left a Flying Raijin kunai hidden within the stone chamber of the Uzushiogakure ruins. His original body then performed an ultra-long-distance teleportation to a cave he had marked in the Land of Rice Fields.
Such a massive jump, spanning more than half the Land of Fire, was a feat only Menma—with his monstrous chakra reserves—could sustain.
The Land of Grass, much like its name suggested, consisted mostly of vast, rolling prairies, with only a few scattered forests along its borders.
The Hidden Grass Village sat at the very heart of this endless sea of green.
On a small hill covered in verdant grass, Uzumaki Karin was following her peers, gathering medicinal herbs.
Compared to the other children of the Grass Village, who laughed and chatted amongst themselves, three-year-old Karin was consistently ostracized. Even the supervising Genin, who spoke gently to the other children while teaching them to identify herbs, looked at Karin with nothing but cold suspicion and guardedness.
Young Karin didn't understand why they treated her this way. She didn't know why the village looked at her and her mother with such complex, twisted emotions.
Whenever she was out gathering herbs or fodder for the village livestock, Karin kept her distance from the others. Yet, if she strayed too far, the supervisor would bark at her to return.
Today's sun was particularly scorching. Karin had been driven to the sunward side of the slope, forced to gather herbs under the unrelenting heat, her small body enduring the bake of the midday sun.
Suddenly, a shadow fell over her, blocking the stinging glare.
Karin, thinking it was the Genin coming to scold her again, looked up timidly.
Standing before her was a mysterious man clad in black, wearing a white three-eyed fox mask. He stood silently, providing a small patch of shade. A gentle breeze swept across the prairie, bringing Karin a long-awaited sense of cool relief.
"Karin! Get away from him!"
A sharp cry rang out from behind her.
A woman wearing a Grass Village headband stood tensely at the crest of the hill. With a grave expression, she whipped several shuriken from her pouch and flung them toward the stranger and Karin.
Whether by malice or a lack of skill, one of the shuriken flew directly toward the little girl.
The steel star grew larger in Karin's vision.
In the blink of an eye, a large hand caught it.
The masked man had flickered in front of Karin, catching all three incoming shuriken with his bare hands. Then—
Shuu! Shuu! Shuu!
He threw them back with far more lethal precision.
The Grass Genin tried to dodge, only to find in horror that the projectiles had completely cut off her path of retreat.
Thwack—
One of the shuriken buried itself deep into her thigh, sending blood spraying onto the grass.
"Agh!" The woman gritted her teeth against the pain and pulled a signal flare from her pouch, yanking the cord toward the sky.
Fweee—!
A red flare streaked upward, visible for ten kilometers across the open plains.
"Your name is Karin, isn't it?"
As the girl stared blankly at the fading trail of the signal flare, a gentle question drifted into her ears.
Behind her glasses, Karin's red pupils trembled. She nodded shyly and whispered, "Who... who are you?"
"I am your clansman."
Menma reached out and patted little Karin's head. The vibrant red of her hair reminded him of Kushina.
"Come. Let's go get your mother. I'm taking you both away from here."
Menma softened his voice as much as possible, afraid of startling the sensitive, rabbit-like child.
"Clansman?" Karin didn't fully understand the word, but she felt an instinctive, deep-seated warmth.
An inexplicable sense of trust and dependence toward this older brother began to bloom in her heart.
Menma took Karin's small hand in his and walked toward the hilltop.
The female Genin at the top was now incapacitated, while the other children had already fled in a panicked scramble down the other side.
The woman held a kunai in front of her chest, her body shaking as tears streamed down her face.
Menma tilted his head slightly. Through the socket of his mask, a crimson Sharingan glared at her.
With just a single glance, the Genin fell into a trance. She turned her kunai inward and ended her own life.
Crossing over the hill, the perimeter fence of the Hidden Grass Village came into view.
It was a simple ring of sharpened logs driven into the earth—a primitive defense that looked like a prehistoric settlement compared to the towering stone walls of Konoha.
Menma led Karin toward the entrance.
By now, the village had seen the signal flare. An interception squad, consisting of one Jonin and three Chunin, had already been dispatched to investigate.
The two parties clashed at the village gates.
"Who goes there!"
Seeing a masked intruder holding Karin, the Grass Jonin didn't hesitate. He drew his short sword and lunged forward, intent on a swift execution. The three Chunin drew their kunai and flanked from three sides.
In the next heartbeat!
The moment the Jonin made eye contact with the swirling crimson in the mask's socket, his body stiffened.
After a second of paralysis, the Jonin's sword suddenly swung toward his own teammates.
Caught off guard, two of the Chunin were cut down instantly.
The third Chunin scrambled back, screaming in terror, "Captain Hucheng! What are you doing?!"
His only answer was Hucheng's hollow gaze and a blood-slicked blade.
If these were Jonin from the Five Great Nations, they wouldn't have been suppressed by a three-tomoe genjutsu for so long. But the Grass was a minor village; their "Jonin" were, at best, equivalent to the Special Jonin of a major power.
Once the last Chunin was dealt with, the captain turned the blade on himself, plunging it into his own throat.
As the body slumped, blood pooling on the ground, little Karin remained eerily calm. In this war-torn minor village, death was a common sight. For a place like this, the shadow of conflict never truly lifted.
Menma patted Karin's head and gently released her hand. His fingers moved into a series of rapid signs.
The Seal of the Tiger!
"Nine Masked Beasts: Svaha!"