"I don't know," Muzan admitted. He didn't understand why he was compelled to defeat Tanjiro.
"I was born to stop you from achieving my absolute freedom."
Their fight raged on as Tanjiro continuously refined all the techniques he had developed. With every exchange, he grew stronger and more skilled.
Despite their progress, the battle remained evenly matched. It was as if they were mirroring each other, with equal strength, experience, and growth. For Tanjiro, this fight was an opportunity to gain invaluable experience and develop his most powerful sword techniques—skills he planned to use in his future travels.
Minutes turned into hours, and as the battle persisted, both combatants rapidly advanced not just in strength, but in expertise. Muzan employed biokinesis, transforming his body parts into bladed whips. He also utilized the demon slayer mark and transparent world, abilities he had acquired from the demon with six eyes, whom he had devoured after the original Muzan.
As the progenitor of demons, Muzan possessed a vast array of abilities. These included demonification, where he could transform humans into demons by injecting his blood, and demon manipulation, allowing him to control demons. His powers were further amplified beyond those of the original Muzan.
Muzan's black blood had the potential to demonify anyone, though he had yet to fully test this ability. He also wielded techniques such as the crescent moon blade from Kokushibo, combined with moon breathing, and cryokinesis from Doma, whom he had previously killed and devoured.
During their fight, Muzan unleashed all his abilities. He combined cryokinesis with biokinesis, coating his bladed whips and sword with ice. Each attack brought a chilling coldness with it.
Despite Tanjiro's use of Transparent World (TW) and Demon Slayer Mark (DSM), each hit from Muzan left him feeling his blood freeze. Even with his enhanced physique, Tanjiro sustained injuries as the battle dragged on, and Muzan's growing experience only made him more formidable.
Muzan unleashed a flesh bomb attack, causing spikes made of flesh to erupt from the ground and spread throughout the battlefield. As the fight continued, even the demons under his control could not withstand the damage, and the Infinity Castle began to collapse.
Each of Muzan's attacks generated increasingly devastating shockwaves. The castle's destruction was inevitable, and Nakime, the demon controlling the castle, eventually succumbed to the damage. Before collapsing, she managed to transfer Muzan outside, bringing Tanjiro with her as the castle crumbled.
Outside the castle, Muzan took a deep breath, observing the ruins before him.
"I should have known this wouldn't be easy," he said, his voice filled with determination. "Tanjiro, I should have turned you into a demon. Sadly, my purpose here is to stop you. To do that, I must kill you with everything I have."
As Muzan continued to watch the collapsing building, a sudden booming sound echoed, revealing Tanjiro standing amidst the rubble. Despite being riddled with minor injuries, Tanjiro's constitution, now 153 times that of a normal human, remained resilient.
"It shouldn't surprise me to see you still standing, Tanjiro," Muzan remarked, studying him closely. He sensed something unusual about Tanjiro—a presence almost otherworldly, characterized by an eerie calmness and an absence of emotion.
"Thanks to you, I've finally achieved what I wanted. Today is the day you die."
Tanjiro, maintaining his composure as if the previous battle had been trivial, responded calmly. "Celestial Breathing, 1st Form: Celestial Dance; Flowing Tides (Mist + Water)."
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* Moments before the infinity collpases completely *
Tanjiro stood amidst the wreckage of the crumbling castle, his gaze fixed calmly on the spot where Muzan had been teleported. Despite having the capability to immediately intercept Muzan, Tanjiro chose not to. Instead, he focused on recalling the Moon Breathing forms he had observed Muzan using.
In a single fluid motion, Tanjiro reviewed each of the Moon Breathing forms from first to sixteenth, his mind processing the intricate techniques with unparalleled speed. Within seconds, he had mastered the Moon Breathing style he had sought.
[ You have successfully learned Moon Breathing(Level 1) ]
Mentally upgrading Moon Breathing to its maximum level, Tanjiro now possessed mastery over all known breathing styles. With this complete repertoire, he was ready to develop his own unique breathing techniques. Drawing on the strengths and advantages of Water, Thunder, Flame, Beast, Wind, Mist, Love, Serpent, Sound, Stone, Sun, and Moon Breathing, Tanjiro crafted the first form of his new style.
"Celestial Breathing 2nd Form: Heavenly Strike; Thunderclap and Blaze."
With a decisive slash, a thunderous crack echoed through the air. Static electricity surged around him, and blazing fire erupted from his sword as it cut upward. The combined force of thunder and flame created a dazzling display of power.
[ You have successfully created your own breathing style: Celestial Breathing.
Benefits of Celestial Breathing:
1. Grants Eternal Lifespan
2. Enhances Physique/Celestial Physique
3. Bestows Celestial Energy
4. Attunes the User to Celestial and Terrestrial Energies (e.g., Earth, Wind, Cosmic, Fire)
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Celestial Physique: A physique obtained upon mastering Celestial Breathing. It aligns the user's body with Celestial and Terrestrial Energies, enhancing their physical capabilities and resilience.
Celestial Energy: A unique energy available exclusively to Celestial Breathing users. It allows the harnessing of both celestial and terrestrial forces, depending on the desired effect. ]
Tanjiro appeared above, his gaze fixed on Muzan, who stood calmly, seemingly unfazed by Tanjiro's arrival.
"System, upgrade the Celestial Breathing," Tanjiro murmured quietly, ensuring Muzan would not hear him. Even if he did, Tanjiro knew Muzan would be unable to discern the meaning behind his words.
[ Upgrading Celestial Breathing... ERROR! ERROR! ERROR! Celestial Breathing cannot be upgraded as it is a host-exclusive creation.
Only the host can enhance their creation, Celestial Breathing, to a higher level.
Don't worry, host. Each creation belongs to you, and you have full control over it, including sharing it with others. However, be cautious—only share your creation with someone you trust. ]
"I see. Well then, only the Kamado family will ever receive this Celestial Breathing. System, please ensure that this breathing technique is shared with every member of the Kamado family. However, if anyone uses this technique to endanger innocent lives, I want you to revoke all the benefits of Celestial Breathing from them. We cannot allow such a powerful technique to be used for chaos."
[ Affirmative, Host. All descendants of the Kamado family will now be able to use Celestial Breathing by birth.
Users of Celestial Breathing will be marked with a symbol: a deep blue central circle with light blue to white radiating lines evenly spread out, a purple lotus petal in the central circle, scattered golden stars along the edges, and an emerald green outer ring. This symbol will only appear when using the breathing forms. ]
Tanjiro faced Muzan with unwavering resolve. "That is nice, thank you. Now then, I will finish this fight once and for all and return home."
He raised his sword, channeling the energy of his newly developed breathing style. "Celestial Breathing 1st Form: Celestial Dance; Flowing Tides."
A sweeping motion of his blade unleashed a torrent of celestial power, blending the elements of water and mist into a powerful, radiant attack that surged toward Muzan.
[ Celestial Breathing 1st Form: Celestial Dance; Flowing Tides - Mimics the flow of water to create fluid, unpredictable movements while using mist to obscure the user's presence and confuse the enemy. ]
Before Muzan's eyes, even with his Transparent World active, Tanjiro's movements were invisible. In an instant, Tanjiro appeared directly in front of him. Muzan tried to react, but he was immobilized before his body was sliced into pieces.
A foreign, indescribable feeling of intense fear overwhelmed Muzan as he felt his body being shredded. He hadn't even seen the attack—Tanjiro stood calmly, his sword halfway sheathed.
"What did you do!?" Muzan's voice trembled with fear.
"Ending you," Tanjiro replied coolly, without hesitation. He activated another form of Celestial Breathing, and a symbol appeared on his left hand.
"Celestial Breathing 6th Form: Luminous Love: Celestial Harmony."
[ Luminous Love: Celestial Harmony (Love + Sun)
- Uses flexible, graceful movements to balance powerful, sun-infused strikes, maintaining emotional and physical harmony. ]
With the combined power of love and sun, Tanjiro delivered multiple strikes, slicing Muzan's body into thin sheets of meat. Despite the hours of intense battle, the fight concluded swiftly with Tanjiro's newly created breathing technique.
"This is the only way I can repay you—killing you with love," Tanjiro said, watching Muzan disappear before him.
"I... see you in the afterlife," Muzan replied, hesitating with an uncharacteristic tone. Smiling faintly, he closed his eyes and finally vanished from the world. As he disappeared, demons across the globe felt their bodies collapse and disintegrate into dust.
Demons engaged in combat with demon slayers, those preparing for their next meal, those held captive, and those poised to strike—all turned to dust as they clutched their beating hearts, succumbing to their final moments.
In no time, all the demons turned to dust, reminiscent of Thanos's snap. Tanjiro, standing where Muzan had fallen, lowered his sword in a gesture of respect and gratitude. Despite their brief encounter, the bond formed through their fierce battle was profound. They were warriors driven by opposing goals—good versus evil, justice versus injustice, order versus chaos. Though their aims differed, their similarities were striking.
Both sought absolute freedom, albeit through different means.
Tanjiro walked away, leaving his sword at the makeshift tomb he'd created for Muzan. Though Muzan was not the original, he had done his best to challenge Tanjiro. In the end, Muzan had underestimated Tanjiro's resilience and potential for growth.
Tanjiro was a force of unparalleled power, and nothing could halt his progress.