Two months. It had taken Izumo Tatsuya only two months to master all the secret forms of Thunder Breathing.
Kuwajima knew his disciple had no idea how exaggerated his talent was. If word of this got out, it would cause an earthquake at the Demon Slayer Headquarters. But here in the morning mist of Mount Momoyama, only the two of them knew.
"Tatsuya, I will not hold back today... show me everything you've learned. Use every method of attack you can think of!"
Tatsuya stood steady, his palms dampening the hilt of his wooden sword. He could feel the overwhelming aura radiating from his master.
Vroom!
Kuwajima moved first! The wooden sword whistled with the weight of a real blade. Kuwajima stepped forward, dropping his center of gravity, and thrust his sword with a momentum that seemed to warp the very air.
"Thunder Breathing, First Form: Thunderclap and Flash!"
It was a straight-line burst that felt like it was rending space itself.
Opening with the finishing move, old man?! Tatsuya's instincts took over. He knew better than to meet his master's full-power lunge head-on. He stepped back half a pace and pivoted.
"Thunder Breathing, Second Form: Rice Spirit!"
His sword didn't block; instead, it vibrated at a high frequency in a tiny arc. Clang-clang-clang! He used the dense, lateral strikes to deflect the trajectory of Kuwajima's thrust, dispersing its power.
"Hmph! A trick! Good adaptation, but your power is too scattered!" Kuwajima didn't pull back. Using the momentum from Tatsuya's deflection, he flipped his wrist and swung the sword upward in a low, rapid arc.
"Thunder Breathing, Fourth Form: Distant Thunder!"
The golden light was like a compressed javelin, aiming straight for Tatsuya's exposed torso.
"It's not a trick, it's a tactic, Master!" Tatsuya slid backward, his blade tapping the ground for leverage, narrowly letting the light graze his clothes. Then, like a compressed spring, he released!
"How about this?! Thunder Breathing, First Form: Thunderclap and Flash—Six Fold!"
"What...?!" A flash of genuine shock crossed Kuwajima's eyes.
The boy's figure didn't just disappear once; he left faint golden afterimages as he flashed from the left, the front-right, the center, and the back... six golden trajectories, slightly curved, forming a web of thunder that converged on the old man.
"Impressive! To use the First Form to this extent!"
Faced with this storm of speed, Kuwajima didn't retreat. He stood like a rock, swinging his sword in a perfect, golden circle around himself.
"Thunder Breathing, Fifth Form: Heat Lightning!"
Bang-bang-bang! Tatsuya's lunges hit the "barrier" like they were hitting a wall of counter-force. His arms went numb, and his momentum was forcibly halted.
"Your strength and experience are still lacking! Fierce, but no follow-through!" Kuwajima critiqued. Seeing the moment Tatsuya's energy dipped, he lunged into the opening.
"Take this—Thunder Breathing, Third Form: Thunder Swarm!"
He became a wraith, circling the gasping Tatsuya with tiny, rapid steps. His sword thrust from impossible angles—the throat, the ankles, the back. It was a buzzing "swarm" of strikes, with the true killing blow hidden in the noise.
I can't keep track! Tatsuya wailed internally. He was being poked and prodded from all sides. But he didn't panic. Under the pressure, his perception hit its peak. He stopped trying to see with his eyes and felt the changes in the air. He raised his sword high and slammed it into the ground!
"Thunder Breathing, Sixth Form: Rumble and Flash!"
BOOM—!
Violent, simulated golden thunder erupted from his sword in a fan shape, tearing through the dirt and grass. It was a move of pure power, designed to shatter a refined, continuous assault.
The swarm was torn open. Kuwajima's figure was interrupted, and he had to step back.
"Correct judgment! You forced me back! But that move drains you—how will you handle the next one?"
The old man moved like a ghost, cutting into Tatsuya's inner circle while the boy was still recovering his breath. It was a plain, unadorned thrust aimed straight at Tatsuya's chest. No golden lights, just pure skill and timing.
It's over... Kuwajima thought, preparing to pull back at the last second.
But as the blade was about to touch his chest, Tatsuya's mouth curled into a smirk. He didn't try to block. Instead, he used the remaining downward momentum from his Sixth Form to snap his core muscles and lean back until he was nearly parallel to the ground!
Using his left hand to brace against the earth, he swung his right leg out like a scorpion's tail, kicking precisely at the pressure point on his master's wrist!
This wasn't a Breathing Form—it was a move he had improvised from being beaten in "Bean Hell."
"What?!" Kuwajima was truly surprised. His wrist went numb, and his sword's trajectory shifted, missing Tatsuya by a hair.
Tatsuya used the momentum to flip backward, landing gracefully several meters away. He panted, sweat dripping from his brow, but he had a cheeky grin. "Hehe, Master, didn't expect that? Breathing is the foundation, but in a real fight, you need some 'dirty tricks,' right? Playing by the book is boring!"
Kuwajima looked at his reddened wrist, then at his glowing, spirited disciple. His sternness melted away like spring snow. He burst into a loud, hearty laugh that echoed across the slopes.
"Hahahaha! Good! A 'dirty trick' indeed! Tatsuya, you brat... in these two months, you've done better than I ever imagined!"
He walked over and slapped Tatsuya's shoulder with pride. "Forms are dead, but people are alive. To master the Forms and then add your own understanding—that is the true first step of a master!"
He paused, then added his habitual critique: "But your timing was off by a hair! If that kick had been half a second slower, you'd be on the ground listening to me lecture you!"
"Yes, Master! I understand!" Tatsuya shouted, his heart full of joy. Even now, he has to get one last jab in... but hey, that's my Master!