Two days ago.
In the aftermath of Kamaro disappearance, the train car fell into a heavy silence, broken only by the rhythmic clatter of the wheels on the tracks.
Maru-ni, the little Shiba Inu, paced restlessly, his nose twitching as he occasionally bared his teeth at a spot where the demon's foul scent still lingered like a stain on the air.
Seated opposite each other, Shinichi and Shinobu wore identical solemn expressions.
The creature's final, mocking words echoed in their minds, a venomous whisper they couldn't shake.
"That was a truly bizarre demon," Shinobu murmured, propping her chin on one hand.
With the other, she reached across the small table and playfully pinched Shinichi's fingers, which he had rested there unconsciously.
Her eyes held a mischievous glint, a stark contrast to the gravity of her words.
"Are we actually supposed to believe a word of its nonsense?"
To trust a demon? A powerful Upper Rank, no less?
The very idea would have been the most ridiculous joke told in the thousand-year history of the Demon Slayer Corps.
And yet… if it was true, the information the demon had so casually offered was beyond terrifying.
It painted a picture of a desperate, unwinnable war, a situation the Corps had never conceived of, let alone faced.
The horror of demons had always been their monstrous individual strength and their bizarre Blood Demon Arts.
But the terror of humanity was its own beast entirely.
The Great War that had just ravaged the world, claiming tens of millions of lives, was a grim testament to that.
Humans had iron discipline and weapons of terrifying destruction.
The thought of that power being turned against them by their own kind was paralyzing.
Shinichi's brow was furrowed in thought, but seeing the deep worry in Shinobu's eyes, he pushed his own confusion aside.
He gently captured her increasingly restless hand, giving it a firm, reassuring squeeze—a silent return for her earlier pinch.
"Who's to say what's true?" he said, his voice steady. "But think about it. If demons could really corrupt the highest levels of government, why wouldn't Muzan have done it centuries ago? It would be far more effective than relying on an army of lesser demons who can only hunt in the dead of night. Besides," he added, a flicker of doubt in his eyes, "that creature's attitude… it didn't feel like it was truly one of Muzan's loyal followers."
"It didn't seem completely loyal to him," Shinobu agreed, her violet eyes widening slightly as she caught his meaning.
"I think… I think it told us that because it wants to use us for some purpose of its own."
"Use us?" A cold smile touched Shinichi's lips.
"To stop Muzan? Maybe even kill him? If that's what it wants, then I'm more than happy to be used."
A genuine, almost dangerous-looking grin spread across his face.
"Tsk, you're no fun, Shinichi," Shinobu pouted, though her spirits seemed to lift.
"I'm just joking here. None of them are good, obviously."
With a rustle of her butterfly-patterned haori, she stood and gracefully moved to the seat beside him.
Shinichi instinctively raised an arm, allowing her to lean comfortably against his side.
Once she was settled, he let his hand rest on her head, gently stroking her dark hair.
"Mmm," Shinobu hummed, closing her eyes in contentment.
The familiar, comforting scent of grass and trees that always clung to him filled her senses.
The warmth of his hand was a little itchy, but in the best way possible.
"That's nice."
"Arf! Grrrr!"
A series of agitated yaps came from the floor.
Maru-ni stared up at them, his big, dark eyes filled with betrayal.
Before Shinobu had come along, and for most of their time in the Corps, he was the one who got Shinichi's exclusive head-rubbing service!
"Alright, alright, Maru-ni, settle down," Shinichi chuckled. "It's almost time for dinner."
"Awooo..." The dog let out a sad, resentful whine, collapsing onto the floor with a dramatic sigh.
ε-(≖д≖﹆)
Leaning against Shinichi, Shinobu cracked open one eye and stuck her tongue out at the sulking dog.
For a moment, the butterfly pattern on her haori seemed to shimmer and cling to her form a little too closely, as if it were a part of her.
If you didn't look too closely at the dangerous purple glint on her sharpened fingertips or the slight elongation of her canines, it would be hard to tell she had become a demon at all.
Shinichi sighed, rubbing his own temples with his free hand.
There was no point in trying to unravel the demon's tangled motives right now.
That was a problem for when they got back to headquarters.
For now, he needed a clear plan.
"Whatever that creature's goal is," Shinichi said, his voice firm, "the threat of infiltration is real. We have to warn Oyakata-sama and the Hashira. Everyone needs to be vigilant, especially when dealing with government or military officials. I'll ask Chinatsu for her help as well, to see if her contacts have noticed anything unusual."
To Shinobu, his words were a steadying force.
She nodded vigorously against his shoulder.
"Yeah, Shinichi's right."
"And about your body, Shinobu..." Shinichi looked down at her. "I'm sure Lady Tamayo's research will help. Don't worry too much."
"Mhm, Shinichi's right," she mumbled again, snuggling closer.
"..."
Suddenly—SNAP!
A sharp, unnatural noise from the end of the car made both of them jolt upright.
In a single, fluid motion, Shinichi's hand was on his Nichirin Blade, the steel clearing the scabbard by inches.
A dangerous purple light pulsed at Shinobu's fingertips.
Only Maru-ni looked up, confused by their sudden, deadly tension.
The door connecting the carriages slid open with a rattle.
A smiling train conductor pushing a dining cart walked in.
"Good afternoon, passengers! Would either of you care for some lunch—eh!?"
The conductor froze mid-step, his polite smile locked on his face.
He stared, wide-eyed, at the two passengers who were now glaring at him with killing intent.
What is this? he thought, his heart hammering in his chest.
'Did I just walk into a gang fight? And why are that pretty girl's fingers glowing!?'
Shinichi and Shinobu glanced at each other, the tension instantly dissolving into shared embarrassment.
"Two lunches, please," Shinichi said, forcing a slightly stiff smile.
"Thank you."
"O-o-okay..." the conductor stammered, quickly handing them two bento boxes before practically fleeing the car.
Once he was gone, the silence returned, this time filled with a much lighter air.
....
Night had fallen by the time they finally arrived back at the Demon Slayer Corps headquarters.
They slipped in under the cover of darkness, their late return purposefully kept quiet to avoid disturbing the other members.
But news traveled fast.
As they crossed the main courtyard, a familiar voice cut through the night.
"Shinobu!!"
A wave of relief washed over Shinobu's face, and she broke into a wide, genuine smile.
"Nee-san!"