Perhaps Tanjiro's departure had cornered the demon controlling the train.
The abnormalities within the carriages intensified. Tendrils of flesh burst from the seams again and again, whipping toward the unconscious passengers.
After fighting at such a relentless pace for so long, Nezuko could feel her breathing beginning to falter.
She wasn't like Kanao, who had trained since childhood.
Though she had learned Breathing techniques and started practicing Total Concentration Constant, her stamina had improved only gradually.
Short fights were manageable. But the longer the battle dragged on, the more her weakness showed.
After slicing through another tendril lunging at a passenger, she paused for a brief instant, using the moment before it regenerated to glance toward the neighboring cars.
Inosuke's energetic shouts carried clearly even from a carriage away.
Takeo, though occasionally stumbling, still managed to keep watch over every passenger. And Zenitsu—despite tearfully complaining—somehow still had enough strength to grumble at full volume while maintaining his Breathing.
Nezuko smiled faintly, a hint of bitterness touching her lips.
Each of them had taken responsibility for a single carriage.
And yet she was the only one already beginning to tire.
[Did I… push myself too far back then?]
"Sis! Behind you!"
She heard the sharp slice of air before the tendril even reached her. Her grip tightened around her Nichirin Blade.
But just as she turned to strike the one behind her, another tendril shot toward a passenger in front.
[What do I do?]
The hesitation lasted less than a heartbeat.
She stepped forward and swung at the tendril threatening the passenger.
Her teacher's words echoed in her mind—
[No matter what, the Demon Slayer Corps' first priority is to protect humans from demons. Even if it costs your life.]
The tendril split in two.
Relief flickered in her chest—
And the air behind her trembled as something closed in fast.
[Looks like I'll have to take this one.]
She adjusted her stance instinctively.
"Thunder Breathing: First Form—"
A flash.
Zenitsu appeared in her vision in an instant. Like a bolt of lightning, he severed the tendril behind her.
Flesh fragments scattered through the air.
Only after sheathing his blade did he calmly finish—
"Thunderclap and Flash: Sixfold."
"…Zenitsu?"
"Nezuko—!"
His face immediately crumpled, as if he were about to burst into tears.
"Are you okay?! You're not hurt, right?! That thing didn't touch you, did it?! Its attacks are so gross!"
"Uh… I'm fine." Nezuko nodded with a soft smile. "Thanks to you. Really, Zenitsu—you were very reliable."
"Y-Yes—! Leave Nezuko's safety to me! No matter what happens, I'll protect you!"
He puffed out his chest proudly—
"Thanks for saving my sister!" Takeo cut in sharply. "But save the chatting for later! Watch your own carriage!"
"Ahhh—! Takeo, you jerk!"
Zenitsu wailed, already gripping his sword.
"I hate this tactless demon! Dieee—!"
In a blur, he dashed back toward his assigned carriage.
Nezuko couldn't help laughing at his miserable cry.
But as she resumed cutting down the writhing tendrils, her teacher's words surfaced once more—
[Even if you must risk your life to protect others, do not worry too much. Your safety will also be guarded by reliable comrades.]
…
Tanjiro stared at the demon before him.
The character [Lower] was carved into its eyes.
He frowned.
No matter how many times he severed its head, it regenerated and rose again—as if it couldn't die.
[Teacher said ordinary demons can't easily overcome the weakness of the neck… Could this be another Blood Demon Art?]
He glanced down at the hand gripping his sword.
[No. My Blood Demon Art cancels his out. That means the real weak point is somewhere else. But the entire train has become the demon. Where is its neck? Am I supposed to tear the whole train apart? And what about the passengers?
And the scent… there's too much interference. I can't isolate the weak point by smell. If Teacher were here… what would he do?]
"How amusing," the demon sneered. "Demon slayers traveling alongside a demon. And you even wield the kind of Blood Demon Art I loathe most."
"There's nothing amusing about it," Tanjiro replied evenly. "My teacher and my family belong to the Demon Slayer Corps. No matter what I am, I have to stand firm so I don't become their burden."
He exhaled slowly.
The mark on his forehead had already spread across his face.
Calming his heart, he replayed every word his teacher had once told him.