As the setting sun of the Land of Iron dyed the castle walls blood red, the great nobleman Fujiwara Masanori used his golden sword to cleave through the final seal. Behind him, the nobles huddled in a corner of the shrine, blood still dripping from the cracks in their armor—just three hours earlier, the iron hooves of the Konoha Kirin Corps had shattered their castle, and rune-inlaid cannonballs had reduced the castle tower to a pile of rubble.
"Rather than be hanged by those Konoha scum, I'd rather the whole world be buried with me!" Fujiwara Masanori's golden sword was stained with his own blood; he had just been grazed in the shoulder by a stray bullet. On the stone platform in the center of the shrine, the totem of the Gate of Hell, carved on it, was gleaming with an eerie black light, and scattered around it were the severed heads of monks—those who had tried to stop them had just been chopped into mincemeat by the nobles.
"My lord, are you sure you want to open it?" A minor nobleman's voice trembled like a leaf in the autumn wind. He saw dark red liquid seeping from the cracks in the stone platform. "The ancient books say that when this door is opened, what comes out..."
"Shut up!" Fujiwara Masanori kicked him to the ground, plunging his golden sword deep into the groove in the center of the totem. "Begging for mercy now? When you were plundering the people with me, didn't you think about the consequences?" He twisted the hilt of his sword, and the totem on the stone platform suddenly lit up. Countless black runes crawled out like living snakes, coiling around the surrounding nobles. "Listen, whatever comes out later, you'll all kneel down and call me master!"
The moment the Gate of Hell opened, the temperature in the entire shrine plummeted. First, a bone-chilling wind surged up from the ground, followed by countless wails and howls, like thousands of blunt knives scraping an iron pot. The cracks on the stone platform grew larger and larger, and the black mist became as thick as ink, through which countless figures could be vaguely seen moving about.
"It's here..." Fujiwara Masanori's voice was trembling, a mixture of fear and excitement. But before he could even assume a posture of submission, a ghostly hand covered in rusty armor suddenly emerged from the mist and grabbed his head. The ghostly hand's nails were sharper than knives, and with a gentle squeeze, Fujiwara Masanori's golden crown shattered along with his skull.
"Ah--!" The scream was cut short. The first demon warrior to charge out was clad in dark red armor, his face hidden beneath his helmet, only a flickering will-o'-the-wisp. His longsword was still dripping with black blood. After felling Fujiwara Masanori, he swiftly slashed at the minor nobleman beside him. The nobleman didn't even have time to scream before he was cleaved in two, his blood splattering onto the Gate of Hell, making the black runes shine even brighter.
In the blink of an eye, the nobles in the shrine were emptied. The demon warriors surged out, stepping over their corpses, their numbers increasing, the dense clanging of armor like a torrential downpour on iron. Some demon warriors were missing arms, some had heads hanging from their necks, and others carried their own entrails, but their eyes all burned with the same ghostly fire. They slashed at anything that was alive, even the stone lions at the shrine entrance were shattered into pieces.
The streets of the Land of Iron quickly turned into slaughterhouses. Commoners who were packing their belongings were pinned to the walls by the long swords of the demon warriors, running children were trampled into mincemeat by the hooves of demons, and even newborn babies were not spared—the demon warriors seemed to have a particular fondness for tearing apart living things, and the demon fire they breathed on people could burn bones to black ash.
The demon warriors in the Gate of Hell seemed endless. From sunrise to sunset, the black mist never ceased, and the corpses on the streets were piled higher than the eaves. Blood flowed into the drains, forming small red rivers. Some daring ninjas tried to set fire to them to drive them away, but the demon fire was more intense than ordinary fire, and instead set the entire block ablaze. The burning corpses sizzled in the fire, like meat being fried.
When the Kirin Corps arrived, this was the Hell scene they witnessed. The 100,000-strong army, arrayed in a square formation, looked like ink on a blank sheet of paper before the Oni Warriors. Legion Commander Hyuga Suzune, wielded a spear that could unleash lightning. "Brothers, let these scum from Hell see the might of Konoha!"
When the first wave of attacks clashed, the light emitted by the runic technology nearly overshadowed the will-o'-the-wisps. The Kirin Corps's specially made Kunai cleave through the armor of the demon warriors, and runic cannonballs could clear a space when they exploded among the demons. Hyuga Suzune's spear swept across, instantly turning more than a dozen demon warriors into charred remains. "Is that all you've got?"
But his words quickly caught in his throat. The cleared space was instantly filled with more demon warriors. Those demon warriors that had been cleaved in two could actually regenerate and continue to slash. A soldier's runic shield was cleaved open by a demon blade, and just Setsuna he was pierced through, his comrade beside him had just cut off the demon warrior's head, but then saw demonic fire spew from the severed neck, burning him into a torch.
"Reserve force, move up!" Hyuga Suzune shouted hoarsely. She watched as her soldiers fell like wheat being harvested, and in the blink of an eye, 30% of the 100,000-strong army was gone. A gigantic demon warrior commander cleaved their rune chariot in two with a single slash; that chariot was capable of blocking Tailed Beast Bomb.
"My lord, let's retreat!" The lieutenant's arm was singed by the will-o'-the-wisps, leaving only bone. "They're endless! The Gate of Hell are still spewing out!" Hyuga Suzune looked back towards the Land of Iron, where the black mist had thickened to the point of being like a black cloth, and countless will-o'-the-wisps could be vaguely seen dancing within it, their numbers impossible to count.
"Retreat..." Hyuga Suzune's spear trembled for the first time in her hand. She watched as the last squad of guards was overwhelmed by the Oni Warriors, their screams mingled with the sounds of exploding runes. The order to retreat was like a stone thrown into water; the remaining soldiers fought their way back, pursued by the Oni Warriors, leaving behind a trail of fallen weapons and limbs.
When they finally retreated back into the Land of Fire and took their headcount, Hyuga Suzune's eyes reddened—of 100,000 elite troops, less than 40,000 returned alive; more than half had been lost forever in the Land of Iron. A soldier with a broken leg hugged his officer's leg and cried, "Sir, I saw them eating our people... those demon warriors that crawled out of the Gate of Hell, they seemed to feed on living people..."
The Land of Iron became a forbidden zone. No one dared approach it anymore. From afar, the land was forever shrouded in black mist, and the occasional wails of ghosts could silence even dogs three miles away. The Gate of Hell remained open, like an insatiable mouth, devouring all life there day and night. And what the Kirin Corps brought back, besides severed limbs, was news that chilled the entire Konoha: it seemed the creatures of Hell hadn't finished emerging, and the greatest crisis facing humankind had arrived.
Konoha convened an emergency meeting to prepare for the great war invading the Shinobi World from Hell. The Fourth Hokage, Kagami Uchiha, decided to personally lead the Anbu and the Konoha Military Police Force into the Land of Iron, and countless veteran ninjas also gathered to volunteer for the battle. This was a war that would affect all of humanity.