Kakashi worriedly looked upwards as he and Sasuke streaked through the skies on the back of Garuda, Sasuke's summoned hawk. Above them, the heavens were already beginning to darken as the moon slowly slid in front of the solar disk, gradually blotting out more and more of the light cast down by the sun.
"There's no telling what Hiruko will do now that I'm free from his puppet jutsu," Kakashi called over the wind whistling in his and Sasuke's ears. "We need to hurry to Mt Shumisen while we still know where he is."
As the saying goes, if anything can go wrong, it will go wrong… and Hiruko's plan was anything but perfect, because it depended on everything going exactly as intended.
Around sixteen years ago, a young Kakashi returned to the village after the fateful battle at Kannabi Bridge, with a Sharingan in his eye socket given as a birthday present by a dying Obito. Upon witnessing this gracious gift of talent, the talentless Hiruko, who constantly compared himself to the Sannin, his childhood friends who had long since surpassed him, at last found inspiration for his path towards longevity: the Chimera Jutsu.
If the heavens would not grant him talent, he would defy fate and take for himself what had never been meant to be his! If the village's propaganda encouraged the villagers to give up everything they had to give for the common good, then he would take all the world had to offer for himself!
All for one was Hiruko's Will of Fire.
Following his instincts, Hiruko planted a dormant jujutsu on Kakashi, compelling him to meet him on Mt Shumisen when it activated years later, so that he might harvest the gifted Sharingan then… without taking into account that Kakashi might die in the meantime, that he might notice the presence of the curse and have it removed, or that he might even resist its effects outright.
And inevitably…
When Sasuke spotted his sensei slaughtering Iwa-nin like a man possessed, he naturally tried to dispel the curse afflicting him and succeeded quite easily, thanks to his Sharingan's hypnosis.
"This Hiruko person will rue the day he set his sights on the Uchiha," Sasuke replied coldly, urging his mount faster towards Mt Shumisen. "Those who try to steal what belongs to the Uchiha will get what they deserve… a swift death at my hands."
Kakashi said nothing, though a chill ran down his spine.
"Remember the plan; I will fight Hiruko myself, so drop me off on Mt Shumisen, then fly back to the village immediately," he said at last. "The village needs your strength; there's no need for you to risk your life here."
Kakashi was ready to give up his life for the good of the village, and though his disciples, his friends, if he still had any, and his rival, Guy, would grieve in the days following his passing, they would one day move on beyond that sorrow. As long as they lived, everything would be all right, because while they remained alive, their futures were limitless.
Self-sacrifice was Kakashi's Will of Fire.
"I can't obey that order," Sasuke replied shortly. "If you lose, your Sharingan will be taken. You're the only person that Uchiha clan member recognised, so you're the only one who should have that eye."
Kakashi couldn't bring himself to explain that he intended to sacrifice himself in order to kill the invincible Hiruko from within, using his Kamui to directly twist the space-time within him and bypass his resistances. He knew that, of all the explanations he could offer, the truth was the only one Sasuke would never accept.
"Furthermore, I doubt this Hiruko person will be satisfied with just one eye," Sasuke went on. "If he obtains your Mangekyō Sharingan, he'll come after Sakura and me next armed with your powers, and I can't accept putting her in unnecessary danger."
Sasuke had witnessed firsthand how Kakashi had torn a chunk out of Deidara from a distance, tearing the very space he occupied just by looking at him. Although Deidara had subsequently escaped, he could very well have died instantly if Kakashi had aimed better.
Garuda suddenly shrieked, flapping its wings and rearing up to brake in midair as an enormous fireball burst through a cloud below and roared past them. Spotting a second fireball hurtling up towards them, the bird rolled in midair to avoid the follow-up attack, forcing Kakashi and Sasuke to hold on for dear life by gluing themselves to its back with chakra.
"Wait, I know this jutsu!" Kakashi called. "Sasuke, isn't this…?"
"Yeah," Sasuke replied grimly as he urged his mount into a dive. "It's Kirin. I don't know how the enemy obtained it, but we have to get out of the sky now."
Kirin was the ultimate technique Sasuke had developed with Kakashi's guidance during their two-and-a-half-years training journey across the continent, inspired by Sakura's battle with Kurosuki Raiga.
During that fight, Raiga had used his Kiba twinblades to call down a lightning bolt, which Sakura had split, at the cost of shattering her arm. At the time, Sasuke had been struck by the speed of the attack; surely, he reasoned, even Itachi wouldn't be able to dodge something like this… but, unfortunately, he never got to test Kirin against his brother, as Itachi ultimately succumbed to complications from his illness.
In any case, the fireballs launched into the air were only the first step; their purpose was to warm the moisture-laden air and force it to rise. As it ascended, the air would expand and thus cool down, causing the water particles to condense into a cumulonimbus cloud, thanks to the lower pressure and temperature conditions at higher altitudes.
Collisions between the water droplets within the cloud would increase exponentially, generating electrical charges… and when enough negative charge had built up to break down the atmosphere, natural lightning would discharge, striking the tallest object near the jutsu caster, at speeds many orders of magnitude faster than the speed of sound.
Since the speed of sound was the maximum speed even the fastest of shinobi could achieve, this made the Kirin undodgeable, as long as the target was properly marked… but that being said, electricity always follows the path of least resistance. Sasuke, Kakashi and Garuda were currently the highest objects around by far, and their bodies were much more conductive than air…
Storm clouds began condensing rapidly overhead, darkening the sky far faster than the solar eclipse could ever hope to. Sasuke's and Kakashi's hair stood on end as the mass of negative charges above repelled the electrons on their scalps, leaving their individual strands of hair positively charged…
"Come on, Garuda," Sasuke whispered, stroking his mount's feathers. "Faster, faster!"
The ground was rushing up towards them fast. As long as they made it past the mountain's peak, they would be more-or-less safe, since the lightning would target the then tallest structure in the vicinity…
"We're out of time," Kakashi said calmly, watching as the dark clouds burst overhead, unleashing a torrent of rain. "Get ready."
Blue electricity sparked along Kakashi's and Sasuke's fists, and together, they raised their lightning-wreathed hands towards the heavens, as if daring the Raijin themselves to strike them down with their tribulations.
"Chidori!" yelled Sasuke!
"Raikiri!" shouted Kakashi!
There was a flash of blinding light, and then…
KRAKOOOM!!