Tanjiro raised his Nichirin and fixed his gaze on Rui, settling into his stance.
"I'm about to attack. Be careful."
"I want it…"
"Hm?"
"I want it. I want it so badly." Rui stepped forward, almost without realizing it, and tilted his head up to stare at Tanjiro.
"Those bonds—I want them more than anything. Even after becoming a demon, you still haven't forgotten your family. You still protect them so gently. That's what real bonds are. Hey, why don't you become my big brother? If you do, I'll let those two go. What do you say?"
Tanjiro blinked, genuinely puzzled.
"First, there's no way I'd become your family. And even if we were, you're older than me. How could I be your big brother?"
Takeo, while Nezuko wrapped his wounds, twitched at the corner of his mouth.
[No… I don't think age is the problem here.]
"Why won't you be my family?" Rui stared at him. "You're a demon, aren't you? Humans would never accept you. Only I would stay by your side."
"That's true. I am a demon now," Tanjiro said evenly. "But I know what I want. I want to remember the precious memories I shared with my family. I want to stand with them under the sunlight again. I want to protect them from harm."
He paused for a moment before continuing.
"Even if I can never become human again, I won't abandon my family. Even when I lost my memories—when I couldn't even remember their faces—the only thing I thought about was protecting them… And I'm not some object. I have my own thoughts and feelings. How could I throw my family away just because you said a few words?"
"Such deep bonds," Rui said with a faint smile, not the least bit offended. "It moves me. I don't think there are words that could describe what I'm feeling right now. But since we're both demons, that makes things simple. I'll just take it by force. With absolute strength, I'll carve those bonds into you through fear—"
"That's not what family is!"
Rui turned toward Nezuko.
Her eyes were red-rimmed, but the fury blazing within them was enough to make anyone's heart tremble.
"Family built on fear isn't family at all! Bonds like that have to be cared for. Both sides have to protect and cherish them! You can't steal a family. You can't crush people with fear and call that a bond!"
Nezuko shouted.
"You have no idea what my brother went through to protect us! If he'd had a choice, do you think he would've become the very demon he hates most? Someone like you—who only knows how to force others, who only knows how to take to satisfy yourself—you'll never have a real family!"
Tanjiro's expression hardened. He swung his blade to the right, crimson flames coiling along its edge as they sliced through every thread lunging toward Nezuko and Takeo.
"What are you doing?!" Anger finally broke through his usually gentle expression. "Trying to kill someone just because they told the truth? That's despicable. I'm your opponent, aren't I?"
"She was the one spouting nonsense. How could my bond with my family be fake?" Rui's face darkened. "I've decided. I'll kill them first. Then we can talk. Blood Demon Art: Killing Thread Cage!"
The thin red thread in Rui's hand suddenly spread outward, expanding into a web that engulfed Tanjiro, Nezuko, and Takeo as it twisted in to slice them apart.
"I said—" Tanjiro's crimson eyes blazed, the mark at his temple spreading and deepening in color. "Your opponent is me!"
As he spoke, twin streams of crimson flame intertwined and surged back against the web.
Rui's eyes narrowed when he saw that after burning through the threads, one stream of flame raced along the strand still connected to his fingertip, shooting straight toward him.
With a slight frown, he snapped the thread at his fingertip. A flicker of irritation crossed his face as countless fresh scarlet strands lashed out toward Tanjiro.
"A Blood Demon Art of flames? How troublesome."
Tanjiro didn't give him time to think. Gripping his blade, he closed the distance in an instant. The dark red edge, wreathed in crimson fire, tore through every incoming strand like a raging dragon.
It was a clash between demons—not just of Blood Demon Arts, but of instinct and battle sense.
Silk as hard as steel tangled against scarlet flames. Fine cuts opened across both of them again and again, only to heal almost immediately.
[So fast… Even if it were me—even if I could see them—I still wouldn't keep up…]
Takeo stared at the dazzling exchange, his heart pounding.
[Brother must have gone through hell under Mr. Yoriichi… But can anyone really reach this level through training alone?]
"So fast… I can't even see them…" Nezuko said anxiously as she supported him. "What's happening?"
"They're evenly matched… No—Brother's at a disadvantage." Takeo strained to follow the afterimages of the two figures. "He's been busy cutting down the threads aimed at us, so he hasn't had the chance to counterattack… Damn it. I still can't help at all!"
"So right now… we're just holding him back, aren't we?"
Takeo glanced at Nezuko, then lowered his head.
"…Yes."
"I understand." Nezuko gripped his arm and hoisted him onto her back. "I'll get you somewhere safe first. I can't keep up with their speed or see the whole battlefield—I'll need you to guide me, Takeo."
After slicing through another strand Rui had driven into the ground, Tanjiro caught sight of Nezuko retreating with Takeo out of the fight.
[Good. You're out of danger.]
A faint smile touched his lips. When he looked back at Rui, though, his eyes had gone cold.
"Be careful. I'm done holding back."
White mist spilled from Tanjiro's mouth as his blade surged faster still, and Rui's eyes narrowed.
Judging by his age, this demon couldn't have existed for more than ten years—probably even less. And if he was aligned with the Demon Slayer Corps, someone must have been supplying him with blood to sustain him. By all logic, a demon like that shouldn't be able to match him.
Yet in speed, strength, and regeneration, the demon before him wasn't inferior in the slightest.
Fury flared in Rui's chest.
Why did he have everything Rui longed for? How could a newly turned demon stand on equal footing with him?
Gritting his teeth, Rui wove countless scarlet threads before him, forming a massive, spiraling cocoon. The air itself shrieked as it was sliced apart. Locking onto Tanjiro as he charged, Rui thrust both hands forward.
"Blood Demon Art: Engraved Line Rotation!"