Konoha, Year 37. Rain poured endlessly over the Hidden Leaf Village, dark clouds blanketing the sky as the steady rhythm of raindrops soaked rooftops, streets, and even the hearts of its people. The air carried a heavy scent—wet earth mixed with iron, the unmistakable smell of war. The Second Great Ninja War was in full swing, and reports from the front lines returned daily, bringing more names to be carved into the Memorial Stone. Because of this, the Ninja Academy had advanced the graduation exams. Children would become shinobi early, and shinobi would be sent to war.
On the training ground, a group of children around ten years old stood in formation, some clenching their fists, some trembling, others whispering nervously.
"Next… Kurogane Ren."
The Chunin instructor Daikoku called out the name without much emotion, his damp uniform clinging slightly as the paper in his hand curled from the rain. From the crowd, a boy stepped forward—black hair, black eyes, slim build, and an expression far too calm for his age.
"Present."
His voice was clear as he walked to the throwing line and pulled out three shuriken. Whispers followed immediately.
"Isn't he the one who got full marks in theory?"
"Yeah, but his chakra is terrible."
"He's definitely failing this."
Kurogane Ren ignored them. Instead of focusing on the target, he raised his gaze slightly, observing the swaying trees, the direction of the wind, and the rhythm of the rain. His mind began calculating.
Wind direction northwest. Wind speed moderate. Humidity high. Distance twenty meters.
Even in a world governed by chakra, he relied on something else—science.
He moved without exaggerated posture or wasted motion. Lift. Flick. Release.
The three shuriken cut through the rain, their paths bending under the influence of the wind. For a moment, it seemed they would miss.
Then—
Thud. Thud. Thud.
All three struck perfectly, forming a precise triangle around the bullseye.
Daikoku raised an eyebrow. "…Full marks." A hint of surprise appeared on his face. "You understand how to use the wind. Not bad. Though your power is lacking."
Kurogane Ren gave a small nod, correcting silently in his mind—it was not instinct, but calculation.
"Next, Ninjutsu test."
Daikoku pointed toward the testing area. "This is the main evaluation. In this world, without chakra, skill means nothing."
Ren took a slow breath and formed hand seals.
Ram. Snake. Tiger.
"Clone Technique!"
A puff of smoke appeared and two clones formed beside him. However, they looked unstable and faint, one flickering as if it might disappear at any moment.
The surrounding students fell silent. Then quiet sighs spread.
Daikoku shook his head as he wrote on the evaluation sheet. "Chakra control acceptable. Hand seal speed average. But your chakra reserves are too low. How many clones can you maintain?"
"…Two."
The clones vanished, and Ren felt the emptiness instantly as his chakra was exhausted. No powerful bloodline, no special physique, no hidden advantage—just ordinary.
"Kurogane Ren… pass."
Daikoku handed him a forehead protector, his tone lacking warmth. "If this were the battlefield, you'd be in danger. With your chakra level, once the fight drags on, you will die very quickly."
He wrote two words on the sheet:
Mediocre.
Ren looked at the cold metal forehead protector in his hand, and a faint smile appeared on his lips.
Mediocre?
Good. Perfect.
The weak die early. The strong attract attention. Only the mediocre survive long enough to grow.
"Next—Minato Namikaze!"
The atmosphere instantly changed as a blond boy stepped forward with a bright smile despite the rain. As he passed Ren, he paused.
"That throw earlier was amazing. How did you do it?"
"Intuition," Ren replied without hesitation. A simple lie.
Minato smiled and walked forward.
What followed was overwhelming. Every shuriken hit perfectly. Some even collided mid-air before striking hidden targets. His movements were flawless and effortless.
"A genius!" Daikoku's voice trembled with excitement.
Not far away, another boy stood silently with arms crossed, the fan-shaped crest of the Uchiha clan visible on his back.
But Ren had already turned away. His thoughts were elsewhere—calculating, designing, planning.
Low chakra was a problem. So he would solve it.
If he couldn't improve his "software"…
He would upgrade his hardware.
Explosive tag formulas. Chakra-conductive metals. Weapon optimization.
A sharp, dangerous light flickered in his eyes.
"This world relies on chakra…"
"…but I'll change it with science."
The rain continued to fall over Konoha, unaware that something had already begun to change.