The engagement with Tobirama Senju was inevitable. If Hashirama was the heart of the Senju, Tobirama was the brain. He was the one who codified their techniques, the one who saw the Uchiha not as rivals, but as a biological problem to be solved through logistics and counter-measures. And after the "Verdant Singularity" incident at the Naka River, I knew I was at the top of his list for deletion.
We met at the "Grey Plateau"—a desolate stretch of basalt and volcanic ash that offered zero cover. It was a technician's dream and a soldier's nightmare. The wind here was a constant 30-knot gale that tasted of dry stone and old thunder.
Tobirama stood fifty meters away. He was younger than I remembered from the scrolls of the future, his white hair spiky and his red eyes filled with a cold, calculating light that mirrored my own. He wore the blue Senju armor, but it was modified—slighter, designed for the high-velocity movement he was already mastering.
"Uchiha Kaito," Tobirama said, his voice carrying clearly across the plateau despite the wind. "The anomaly. My brother says you are a child of logic. I say you are a glitch in the system that needs to be patched."
"A glitch is just an undocumented feature, Tobirama," I replied. I stood beside Madara, my hand resting on the hilt of my new bismuth-alloy tantō. "And you are still using legacy hardware. Your Water Release relies on atmospheric humidity. On this plateau, the humidity is currently at eight percent. Your conversion efficiency is going to be abysmal."
Tobirama didn't smile. He didn't need to. He slammed his hands together in a single, fluid motion.
"Water Release: Water Colliding Wave!"
He didn't pull water from the air. He pulled it from the earth—from the deep aquifers beneath the basalt. A massive wall of water erupted from the ground, flooding the plateau in seconds. He was literally changing the humidity of the battlefield to suit his needs.
Technical Assessment:
Tobirama's chakra output: Massive.
Environmental manipulation: Successful.
Counter-strategy: Phase Change Induction.
"Madara, now!" I commanded.
Madara didn't use a fireball. He slammed his palms into the water at our feet. But he didn't release heat. He used the Frost-Sink tags I had developed in the forges.
These tags were the inverse of explosive tags. They utilized a localized Yin-release seal to absorb thermal energy at a rate of 4,000 joules per second. As Tobirama's wave hit our position, the water didn't wash over us. It froze instantly.
A jagged wall of ice erupted from the plateau, locking Tobirama's wave in place. The transition was so sudden that the internal pressure of the wave caused the ice to shatter, sending a cloud of razor-sharp frost into the air.
Tobirama moved. He was a blur—the Hiraishin wasn't perfected yet, but his Shushin was so fast it was functionally the same in a short-range engagement. He appeared to my left, a blade of pressurized water extending from his palm.
Internal Analysis: Attack Velocity—35 m/s. Trajectory: Transverse. Predictive window: 15ms.
"Predictive Analysis," I whispered.
My three-tomoe Sharingan tracked the displacement of the air. I didn't try to block the blade with steel. I dropped to the ground and used a Phonic Burst—a localized explosion of sound—to disrupt the surface tension of his water blade.
The water blade shattered into mist. Tobirama's eyes narrowed. He lunged again, but this time, he was met with Madara's bismuth tantō.
The two blades collided. The sound was not the clash of steel, but a high-pitched, metallic shriek that made the air itself vibrate. The bismuth alloy, vibrated by Madara's chakra at exactly 880Hz, began to resonate against Tobirama's steel blade.
I saw the micro-fractures forming in Tobirama's sword. He saw them too. He jumped back, his eyes darting to the bismuth blade.
"Resonant frequency," Tobirama muttered, his voice cold. "You are attacking the metal itself."
"Efficiency, Tobirama," I said, stepping forward. "Why fight the man when you can fight his tools? Your armor is next. The rivets are made of a low-grade iron alloy. One more Phonic pulse and your plates will fall off like dry leaves in autumn."
Tobirama stood his ground. He was analyzing us, his mind working as fast as mine. He saw the "Phonic Wall." He saw the "Frost-Sinks." He realized that the Uchiha were no longer just a clan of fire-breathers. We were a clan of technicians.
"This isn't war," Tobirama said, his voice sounding like a clinical diagnosis. "This is... an industrial slaughter."
"It is whatever it needs to be to ensure the system survives," I replied.
The engagement ended in a stalemate. Tobirama realized he didn't have the data to overcome our new tools, and I knew that if the fight lasted more than five minutes, our chakra reserves would hit the 'Red' while he still had plenty to spare. We both backed away, the fog of the ice-clash hanging between us like a cold shroud.
As we walked back to the compound, Madara was silent. He was looking at his bismuth blade, watching the way the orange sunset played off the micro-serrations.
"He was afraid, Kaito," Madara said softly. "Tobirama. I saw it in his eyes. He wasn't afraid of our fire. He was afraid of the math."
"Fear is a manageable variable, Madara," I said. "But don't get cocky. He is going home to do his own math. And the next time we meet, the plateau won't be grey. It will be red."
We entered the compound, the soot and smoke of the forges welcoming us back. The architecture of attrition was almost complete. Soon, the world would realize that the Uchiha didn't just have eyes. We had a plan.
System Log: Level 3 Optimization Complete. Combat Efficiency: 99.8%. Physical Integrity: 42%. Current Objective: Recovery and DNA-debugging. Secondary Objective: Assess Madara's psychological shift.
The Warring States Era was no longer a war. It was a laboratory. And I was the one conducting the final experiment.