The ruins of the ancient city seemed to stretch on forever, every corner revealing more secrets about the civilization that had once thrived here. Tanjiro, Nezuko, Gon, and Killua moved carefully through the forgotten streets, their senses heightened after their discovery of the murals.
The air felt different now. Heavier, but also alive with an ancient energy that seemed to pulse from deep within the city itself. Tanjiro could almost feel the power of those who had once lived here—the warriors who had mastered breathing techniques in ways he could barely comprehend. He held the knowledge from the tablets close to his heart, knowing that it would change the way the Demon Slayer Corps fought. Yet, he still hadn't uncovered the full extent of their abilities.
"There's so much more to learn," Tanjiro whispered to Nezuko, who hummed softly beside him. She had been on edge since they entered the deeper parts of the city, her keen senses picking up on something that made her wary. Every so often, she would glance toward the shadows, as though expecting something to emerge from the darkness.
Gon, walking a few steps ahead, turned back with his usual bright grin. "Tanjiro, it's amazing how advanced they were, right? I mean, the way they lived with their breathing techniques must have been incredible. I wonder what it would have been like to see them in their prime."
Killua, less enthusiastic but ever sharp, added, "Yeah, but don't forget—there's a reason this place is in ruins. These people lost control of that power, and we've already seen what it turned them into."
Tanjiro nodded solemnly, recalling the mural of the demon transformation. "We need to be cautious. These techniques… if used the wrong way, they can become dangerous."
The group came to a large courtyard in the heart of the city. At its center was a colossal statue of a warrior, his face chiseled with an expression of determination. He was dressed in the armor of the ancient kingdom, his hands outstretched as if he were about to enter battle. Around him, broken pillars and crumbling arches told the story of a civilization that had once been proud and powerful.
Nezuko stared up at the statue, her eyes wide as she studied the warrior's features. There was something familiar about him, as though he had been part of her memories long before she had ever seen this place.
Tanjiro's gaze followed hers, and his breath caught in his throat. "This must have been one of the first users of the true breathing techniques," he murmured, his voice filled with awe. "Look at the way he's positioned—he's not fighting, but it's like he's radiating strength just by standing there."
Gon walked up to the base of the statue and ran his hand along the stone. "It feels powerful, even now. Like there's still some of their energy left here."
Killua crouched beside one of the broken pillars, his sharp eyes picking out faint symbols carved into the stone. "These markings again," he muttered. "They're similar to the ones we saw in the murals. The passive strength these warriors had must have come from mastering breathing techniques to the point where their bodies naturally adapted to it—almost like it became part of their biology."
Tanjiro knelt beside him, his brow furrowed in concentration. "Do you think that's how they maintained their strength without needing to constantly fight? They must have breathed in a way that let their bodies stay in peak condition, even when they weren't in battle."
Killua nodded, his expression thoughtful. "That's my theory. It's like they optimized their bodies for efficiency. If they could control their breathing at a constant level, it would regulate their heart rate, oxygen intake, and even the flow of energy through their muscles. Over time, their bodies would adapt, becoming stronger without having to strain themselves."
Tanjiro's eyes widened at the implications. "So, the breathing techniques we use now are just a fragment of what they could do. We use it in bursts, but they must have trained their bodies to be in a state of constant breathing—always keeping themselves at peak performance."
Nezuko, her eyes glowing softly in the dim light of the ruined courtyard, hummed in agreement. She could sense the traces of power that lingered here, and though she couldn't fully explain it, she knew that the ancient warriors had achieved something far beyond what the current Demon Slayer Corps was capable of.
Gon, ever curious, asked, "Do you think you can learn to do that, Tanjiro? To always be strong like them?"
Tanjiro stood, his hand resting on the hilt of his sword as he looked up at the towering statue. "I don't know if I'll ever be able to reach their level, but I can learn from them. If I can even understand the basics of what they did, it could change the way the Demon Slayer Corps fights. We could be stronger, faster—more prepared to face demons without having to exhaust ourselves every time."
Killua smirked, crossing his arms. "You're already pretty strong, but with this? You might surpass even the Hashira."
The thought sent a shiver down Tanjiro's spine. Surpassing the Hashira seemed impossible to him, but if the ancient techniques could give him and the others that edge, maybe the war against demons could finally turn in their favor.
The Cursed Guardian
As the group explored the courtyard, they noticed something strange. The air, once still, began to stir, and a low rumbling noise echoed through the ruins. Nezuko's body tensed, and she growled softly, her eyes darting around as she sensed something dangerous approaching.
Killua's eyes narrowed. "Something's coming."
Gon, ever alert, clenched his fists, his nen flaring around him. "It's strong. Whatever it is, it's big."
Tanjiro, his senses honed from years of training, felt it too—a presence, dark and oppressive, approaching from the shadows of the ruined city. He drew his sword, the blade gleaming in the dim light as he prepared for whatever was coming.
From the far end of the courtyard, a massive figure emerged from the darkness. It was humanoid in shape, but its features were twisted and grotesque, its skin pale and stretched over muscle and bone. Its eyes, sunken and glowing with a faint red light, locked onto the group as it let out a low, guttural growl.
Nezuko immediately moved in front of her brother, her claws extending as she bared her fangs at the creature. The presence of the demon-like figure triggered something primal within her, a recognition of the curse that had created it.
"It's one of the ancient warriors," Tanjiro whispered, his heart sinking. "But it's been corrupted. This must be one of the first demons—one of the royal bloodline, cursed by the god."
Killua's eyes darted between the creature and the mural they had seen earlier. "So this is what happens when they lose control of the breathing techniques. They turn into monsters."
The creature roared, its voice echoing through the ruins as it charged toward the group with terrifying speed. Tanjiro reacted quickly, activating Hinokami Kagura as he lunged forward to meet it. "Hinokami Kagura, Dance!" His blade cut through the air, striking the creature across its chest in a burst of fiery light.
But the demon-like warrior barely flinched. It swiped at Tanjiro with one massive hand, forcing him to leap backward to avoid the blow.
"It's strong!" Gon shouted, rushing forward with his own attack. "Jajanken: Rock!" He slammed his nen-infused fist into the creature's torso, sending a shockwave through the ground.
The creature staggered but didn't fall. It growled in anger, its red eyes glowing brighter as it turned its attention to Gon.
Killua zipped around the creature with blinding speed, his Godspeed crackling with electricity as he struck it with precise blows. "This thing's not going down easily!" he called out, dodging another swing from the creature's massive arm.
Tanjiro, breathing heavily, realized what they were up against. "It's not just a demon—it's one of the ancient warriors, and it still has some of its power from the breathing techniques!"
Nezuko, sensing her brother's distress, growled fiercely as she charged at the creature, her claws slashing through the air. She struck the creature across its back, her demonic strength tearing into its flesh. But even her powerful attack only slowed it down momentarily.
The creature howled in rage, swinging wildly as it tried to grab Nezuko, but she was too fast, darting out of its reach with incredible agility.
"We need to take it down before it regenerates!" Killua shouted, his eyes narrowing as he focused on the creature's weak points.
Tanjiro nodded, his mind racing. He could feel the power of the ancient breathing techniques coursing through the creature—it was what made it so strong, so resilient. If he could tap into even a fraction of that power, he might be able to defeat it.
"Gon, Killua—keep it distracted!" Tanjiro shouted, his voice filled with urgency. "I have an idea!"
Gon and Killua didn't hesitate. They launched themselves at the creature, their attacks landing in quick succession as they forced it back toward the edge of the courtyard.
Tanjiro closed his eyes, focusing on his breathing. He thought back to the murals, to the tablets he had studied—the way the ancient warriors had mastered their breathing to the point where their bodies were in a constant state of strength. He couldn't achieve that level yet, but he could mimic it.
With a deep breath, Tanjiro steadied himself, letting his breathing become slow, controlled, and rhythmic. His body began to feel lighter, stronger, as the breathing technique took hold. He could feel his muscles relaxing, his stamina returning even in the heat of battle.
Opening his eyes, he charged forward, his sword blazing with the fiery energy of Hinokami Kagura. "Hinokami Kagura, Sun Halo Dragon Head Dance!" he called out, his blade slicing through the air with incredible speed and precision.
The creature roared as Tanjiro's strike connected, cutting deep into its flesh and severing one of its arms. It staggered backward, its regeneration slowed by the overwhelming power of Tanjiro's attack.
Nezuko, seeing her brother's success, growled fiercely and leaped at the creature, delivering a final, devastating blow with her claws. The creature let out a final howl before collapsing to the ground, its body dissolving into ash.
Panting heavily, Tanjiro sheathed his sword, his body trembling from the effort. Nezuko rushed to his side, her eyes filled with concern as she placed a comforting hand on his shoulder.
Gon and Killua joined them, both breathing heavily but grinning with satisfaction. "You did it, Tanjiro!" Gon said, his eyes shining with admiration.
Killua smirked, crossing his arms. "Looks like you're getting the hang of those ancient techniques."
Tanjiro smiled weakly, nodding. "It's a start… but we still have a long way to go."
As the group stood in the courtyard, surrounded by the crumbling remains of the ancient kingdom, they knew that their journey was far from over. The true power of the breathing techniques was still beyond their reach, and the curse of the ancient god continued to loom over them.
But they were stronger now, and together, they would uncover the truth behind the ancient civilization—and the demons that still haunted their world.