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Cold wind blew. Snow fell, covering the forest ground in white. Grey clouds blotched the sky, blocking the sun's warmth and drowning the world in freezing darkness.

It was during New Year's Eve when he was patrolling around Nishiazuma and encountered a peculiar demon.

Growling threateningly, the demon stood in front of him. Its red eyes were slitted and its snarl revealed deadly fangs, as its clawed hands flexed ready to retaliate. Saliva streamed down its mouth, indicating its desperate hunger for flesh. It was a newborn demon who should be killed immediately before it could prey on people and get stronger.

But the demon was small. Very small. Its height didn't even reach past his waist. And it was trembling in fright, weak and helpless as it glared at him with tears in its eyes. It must have been just a young boy when Kibutsuji Muzan turned him into a monster.

But what shocked him the most was an even smaller girl hiding behind the demon. A human girl.

It was on New Year's Eve when Tomioka Giyuu found them, in a small hut dyed in blood, surrounded by the corpses of their dead parents.

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Fortunately, the demon boy could speak.

"M-my name is Tanjirou, and this is my baby sister Nezuko," the demon said, before bowing low. "Thank you for helping us b-bury our parents."

Giyuu stared down at the demon blankly. He didn't know what he was doing. Didn't understand why his hand chose to sheath his sword. The demon was right here, right in front of him. He was a Demon Slayer, and it was his job to kill the demon.

But the demon was so… small. Very polite and unthreatening. It felt like talking to a nice kid rather than a man-eating monster. Ignoring the slitted eyes, the fangs and the clawed hands, this demon behaved just like a human would.

"...How old are you," Giyuu asked, voice monotonous.

"I-I'm four," the b- the demon answered nervously, before patting the human girl's shoulder. "Nezuko is two."

Four. Four years old. Four fucking years old. And the Demon King turned him into a demon.

Giyuu didn't know he could hate Kibutsuji Muzan even more than he already had.

"...You are a demon," he said to the demon, crouching down so that he was at the same eye level. "You will eat humans. You have to be put down."

The demon blinked. Looked down at his sister, who was hugging the demon's legs.

"What about Nezuko?" the demon asked. "Will you kill her too?"

"No. She is a human. She is to be protected."

"Then," the demon looked up and smiled. "Please kill me, mister."

Giyuu frowned at the demon's smile. It was gentle and serene, as if the demon was resigned that death was the only option. And judging by the demon's previous question, he was willing to be put down for the sake of his little sister. So unlike those demons who devoured their own family in hunger.

Giyuu realised then that he hadn't been seeing this demon as one, but an innocent human child. And he couldn't bring himself to raise a sword against children.

"...I will kill you," he said to the boy. "But… not now. Your sister still needs you."

Hope filled the boy's eyes. He hugged his sister tighter as he bit his lip to hold back his tears. "T-then, what should we do?"

"Come with me," Giyuu said and stood up. "I will bring you to my Master's home. He will be able to take care… of… you…"

A tiny hand held his much larger one, soft and warm against his scarred and calloused skin. Giyuu looked down to see their joined hands, as if it was natural for the boy to hold an adult's hand as he walked.

"We should go now, then," the boy said, tugging at his hand. "It's cold. Nezuko will fall sick."

For the first time since their encounter, Giyuu's eyes softened. He crouched down to lift Nezuko up so that she could sleep in his arm, while his other hand held the boy's hand.

"... What's your name, boy."

"It's Tanjirou!" the boy, Tanjirou, chirped brightly. "What about you, mister? What's your name?"

"It's Tomioka Giyuu."

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