- Y/n Tsugikuni -

Chapter 7 - Seething Rage -

—A Few Years Ago—

The forest crackled under the weight of tension. Leaves shimmered in the heat of something unnatural.

A demon’s body lay shattered beneath the limbs of a massive tree. Guts slithered from its torn torso, steaming in the cold night air. Bits of it still twitched—until a blade carved through its spine, ending the regeneration.

Y/n Tsugikuni’s chest heaved. Sweat dripped into the dirt. His demon slayer uniform was stained with dark crimson, and on his skin, the flame-like mark had returned—rising up from his chest and curling to his left cheek like an open wound.

His sword, still red-hot, pulsed in rhythm with his heartbeat: over 300 beats per minute.

“…It’s not enough,” he whispered, eyes shaking.

The air around him wavered from the heat of his exertion. The demon’s head lay somewhere in the brush, still smoking. Yet Y/n didn’t sheathe his blade.

He turned slowly toward the sound of quiet sobs.

There, peeking through the shattered wooden slats of a ruined house, was a little girl—pale, barefoot, trembling. Her knees were scraped. Blood clung to her cheek, not hers.

She didn’t look at the corpse. Her eyes were locked on him—on the glowing red slash of his sword, and the scorch marks still burning on the forest floor.

Y/n blinked. His breath hitched.

He saw something else. A flicker. A memory.

His own mother, wide-eyed. His little brother’s hand slipping from his grasp. A flash of blood.

The same look.

He walked toward her, his steps slow but steady.

The girl shrieked and backed away.

“Don’t cry,” he said gently, kneeling in front of her. His voice was hoarse, but calm. “Now’s not the time for that… I know it hurts. I know.”

He didn’t reach out. Just knelt there with his blood-slicked blade and fire-marked skin, letting her look at him. Letting her breathe.

“If I had arrived sooner, your family might still be alive. That’s not your fault. But this—this pain you’re feeling? Don’t let it stay locked away.”

He lowered his gaze, guilt barely masked behind steady words.

“I know what happens when it stays locked away.”

Silence lingered. Then, the girl stepped forward and clutched the edge of his haori. He didn’t move.

“I’ll get you somewhere safe,” he said, standing.

—Now—

Y/n stood in front of Kagaya Ubuyashiki, shirt half-open to reveal the long, flame-like mark that crawled across his chest. It pulsed faintly.

“You’re not stable, Tsugikuni,” the master said gently, concern laced in every syllable. “Your heartbeat is constantly above 250 beats per minute. That isn’t sustainable for a human. These marks… they are consuming you.”

Y/n didn’t blink.

“I can still fight.”

“That’s not the question. You fight regardless. But how long before your body says no?”

Y/n gave a small smile. Not cold. Not prideful.

“I was given this strength for a reason, Kagaya-sama. Even if it costs me everything, if one more child lives… then it's worth it.”