Crackle!
Leaving aside Ryuu's battle for the moment, Roy focused on his own opponent. Golden lightning surged from his palm, materializing into a three-shaku-long sword.
The Muramasa Sword's durability was too low. It was already beyond repair, so Roy had no choice but to retire it.
At Lv. 2 with Magic at Rank S, the weapon Roy formed through magic was comparable in quality to the Muramasa Sword. Moreover, it could be created and dismissed at will—extremely convenient.
Facing this young man suspected to be a "messenger of the gods," Kokushibo did not dare be careless. He drew his demon blade, Kyokoku Kamui, activating his Demon Mark and the Transparent World.
The former drastically enhanced his physical abilities; the latter allowed him to see through blood vessels and muscle movement.
Seeing Kokushibo act so cautiously and refrain from attacking first, Roy grinned and made the first move. The muscles in his legs tightened as he shot toward Kokushibo.
He arrived in an instant and slashed.
First Form: Dark Moon – Evening Palace!
Roy's speed startled Kokushibo. His response, however, was swift. Swinging his elongated demon blade, he unleashed crescent-shaped slashes toward Roy.
Clang!
The blades collided with a crisp, ringing sound.
"What immense strength. Among those I have seen, only that lord and Yoriichi Tsugikuni surpass you," Kokushibo said, gripping his sword hilt tightly as he endured the pressure from Roy.
In that brief exchange, both sides had already gauged each other's strength.
A sinister smile curved Roy's lips. He pivoted, avoiding Kokushibo's blade. The sword in his hand dissolved into golden lightning, slithering like a serpent along the length of the demon blade and toward Kokushibo.
Lightning rapidly engulfed his body.
Crackle! Crackle! Crackle!!
The searing sensation from the lightning was no less than sunlight. Kokushibo writhed in agony, his body going numb as he staggered back and dropped to one knee.
Strike while he's down!
Golden lightning surged once more from Roy's palm, forming a massive battle axe that he brought down heavily. Kokushibo rolled aside in fright.
Boom!
The axe split the sturdy floor apart.
Kokushibo's six eyes locked onto Roy and his weapon—more bizarre than any demon.
"Haah!!"
He let out a low roar. Flesh writhed across his body. Two horns sprouted from his forehead. Jagged, uneven fangs extended from his mouth.
Seven or eight grotesque tentacles burst from his back. His appearance twisted beyond recognition, his aura turning ferocious.
Feeling Kokushibo's power rise, Roy narrowed his eyes. This was the demon's true form.
Fourteenth Form: Catastrophic Transformation – Heavenly Crescent!
Kokushibo swung the enlarged Kyokoku Kamui. Overlapping vortex-like slashes—formed from countless blades of Moon Breathing—became a raging tornado.
The sharp crescents tore through the ground, leaving moon-shaped scars as they crushed toward Roy like a tidal wave.
The axe in Roy's hand shifted shape, transforming into a thick shield that he raised before him.
Thud! Thud! Thud!
Countless blade arcs struck the shield with dull impacts.
Bracing himself behind it, Roy inwardly praised his lightning magic. As long as he materialized a weapon, it required only minimal Mind to alter its form. In essence, it was the same spell—versatile and efficient.
Kokushibo appeared at Roy's flank. Curved blade arcs bypassed the shield and attacked him from behind.
Roy instantly reshaped the shield into a spear, blocking Kokushibo's strike.
He had already measured Kokushibo's strength—approximately Lv. 2 with all abilities at Rank A.
Their raw stats were similar. The problem was Kokushibo's swordsmanship and centuries of combat experience, far surpassing Roy's own.
Roy intended to use Kokushibo as whetstone for himself.
Their figures flashed across the ruins of the Infinity Castle, blades crossing and sparks bursting violently. After more than half an hour, Kokushibo was ultimately defeated.
Walking on Wind!
Gales coiled around Roy's legs. Holding a spear, he surged forward like a bolt of lightning, the spearhead instantly piercing Kokushibo's chest.
Kokushibo's pupils trembled. Through the Transparent World, he saw Roy's tensed muscles and predicted the attack—but his body could not react.
Too fast!
Electric current paralyzed his body.
"…Ah."
Kokushibo could not muster even a trace of strength. He knew he had lost.
Boom!
Golden lightning erupted from Roy's palm, burning Kokushibo's body to ashes.
A demon's immortality? As long as it's carbon-based life, claiming to fear neither fire nor lightning is nonsense!
After finishing him, Roy turned his gaze to the other battlefield—Ryuu vs. Muzan Kibutsuji.
Roy had easily eliminated Upper Rank One, Kokushibo, but he did not dare underestimate Muzan Kibutsuji.
The dungeon's upper evaluation limit was Lv. 4. The primary reason was undoubtedly Muzan.
All demons were created by him. Even Kokushibo's strength was separated from Muzan's by a vast, insurmountable chasm.
In the original timeline, the Demon Slayer Corps defeated Muzan only after he had been weakened by a compound drug by ninety-nine percent.
But the one before them was at full strength.
On that battlefield, Ryuu and Muzan's figures intertwined, afterimages flashing.
Boom! Boom! Boom!
Muzan revealed his complete form—long white hair cascading down, mouths lined with fangs opening across his body, eight massive whip-like tendrils lashing with sonic booms.
Even Ryuu found it difficult to approach him.
"Come! Didn't you want to kill me? Lowly ant!" Muzan shouted arrogantly, his whips striking toward Ryuu in blinding arcs.
Ryuu swung her wooden sword, blocking them all.
Yet Roy noticed Muzan's eyes subtly scanning for an escape route. Far from confident, he was inwardly terrified.
Having become a demon a thousand years ago, he dominated the nation for six centuries—until nearly being killed four hundred years ago by Yoriichi Tsugikuni. Ever since, he had lived in hiding.
At the start of this battle, Roy and Ryuu's magic destroyed the Infinity Castle and over a hundred demons. Kokushibo had also fallen. Muzan now stood utterly alone.
At this moment, the Demon King's heart was filled with fear and isolation.
If even a slight opening appeared in Ryuu's offense, Roy believed Muzan would flee immediately.
In previous dungeon runs, Roy could only watch as Ryuu hunted powerful foes.
Now, with Lv. 2 peak-tier stats, he could finally intervene.
Lord of Lightning!
Roy continuously cast his magic. Thunder roared as more and more lightning spears gathered around him.
It carried the feeling of Hedin Selland of the Freya Familia. However, Hedin's magic could generate numerous lightning spears simultaneously, whereas Roy's was single-target and required repeated casting—less efficient.
"Go!"
A dense volley of lightning spears shot forward, raining down upon Muzan.
A shrill scream rang out.
Magic was called a trump card for a reason. Its overwhelming power granted the possibility of defeating stronger foes.
A Lv. 3-tier spell—no Lv. 5 adventurer would dare withstand it with their bare body.