The Shadow Hashira - Tengen X Reader X Sanemi

2

Hi hi ! So as the Y/n is a Shadow hashira I've decided for her to have an all black look like below (I do not own the drawing/picture). Her weapon is a double sided spear and it will GOLDEN! Of course change how she look depending on hair, eyes etc. It is a fanfic after all ;P

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As I waited for the house to fall into a slumber, I listened to the gentle rustling of the cool night breeze. One by one, the lights flickered off, leaving the house in complete darkness. The night had always brought a kind of solace I could never find during the day. Despite my love for the sun, it was the night that held a certain serenity—a silence that felt like home to me.

As the Shadow Hashira, I underwent grueling, secretive training to hone my skills. I work behind the scenes, ensuring the safety and success of the other Hashira without them ever knowing I exist. My identity is a secret even from the pillars of the Demon Slayer Corps. It's a lonely path, but necessary. In the shadows, I can truly be myself, free from the gaze of others.

"Right... it's go time," I whispered to myself, smirking as I vaulted silently from my bedroom balcony, landing softly on the outskirts of the house.

Even after 20 years, I can't help but marvel at the beauty of the estate. Surrounded by towering wisteria trees, the mansion was a safe haven for those healing from battles, protected from demon incursions. The purple petals drifted softly in the wind, brushing against my cheek as I took a deep breath, feeling the coolness of the night air fill my lungs. I adjusted the spear strapped securely to my back and glanced over my shoulder. The house was still, bathed in silence.

Satisfied, I sprinted into the woods, expertly dodging branches and debris. I was fast—faster than any ordinary human. The moon cast my fleeting shadow against the trees, but to anyone watching, it would seem like nothing more than a trick of the light. I had mastered the art of disappearing into the night.

— Travel Back in Time —

"I'm tired!" I complained, breathless, as I struggled to keep pace.

"Tired won't make you stronger," Urokodaki retorted, his voice stern as ever.

I shot him a childish glare, sticking out my tongue, but resumed my relentless sprints up and down the mountain. Urokodaki never went easy on me, and Father had trusted only him to oversee my training. He and Oyakata-sama were the only ones in the entire Demon Slayer Corps who knew I even existed.

"Y/N! You need to focus! If you want to become a true shadow, you must be faster and quieter than the wind itself," Urokodaki shouted, his voice sharp as I panted heavily, feeling like my lungs were on fire.

The mountain air was thin, and every step felt like a battle against exhaustion. I envied the Hashira who could handle this kind of training so effortlessly.

"Yes, Master!" I forced myself to shout back, pushing through the fatigue. Today's training was all about endurance—running endlessly until stopping wasn't even an option.

"Keep going until dusk, Y/N," Urokodaki ordered.

"What?! It's only dawn right now!" I mentally groaned, disbelief washing over me. The idea of running non-stop for that long was borderline torture. But I knew better than to argue. No matter how brutal the training, I had to do it. I had to get stronger—for my new family, for Oyakata-sama.

"See you at the end of the day, Y/N," Urokodaki called, a chuckle escaping his lips as he walked away. Even with his mask on, I could feel the smug smirk. One day, I'd punch him for that.

— Present Time —

I chuckled at the memory as I ran, my legs carrying me swiftly through the forest. Despite how brutal Urokodaki's training had been, it made me who I am today. I couldn't help but grin at the thought of seeing him again—if I didn't punch him harder than last time, I'd regret it.

An hour had passed, and I was now 40 kilometers away from the estate. The night air was refreshing, and as much as I hated the intense training back then, it had paid off. Running like this felt good now.

I soon arrived at my secret training ground, a small pond illuminated by the soft glow of the moon. The surrounding wisteria trees, ancient and towering, gave the area a serene, otherworldly beauty. The water shimmered with a pale blue glow, reflecting the purple hues of the trees. This place had always been my sanctuary—a place where I could train in peace, or just sit and let my thoughts drift.

I settled under one of the trees, my mind wandering back to something I overheard earlier.

"I can't believe there's a demon in the Entertainment District..." I recalled Father discussing the next mission for one of the Hashira. He hadn't yet chosen who would handle it. Giyu? Calm, collected, but perhaps not the best at blending in. Mitsuri, maybe? She'd fit in more naturally in such an environment. Either way, it wasn't my place to interfere. My job was to shadow the chosen Hashira, providing support only when necessary.

"Alright, enough thinking," I muttered, standing up and brushing off the lingering thoughts. I unsheathed my spear, feeling its familiar weight in my hands.

"It's time to train."

I planted the spear firmly in front of me, focusing on the connection between my mind and body. Urokodaki had always taught me to become one with my weapon, to let it flow through me in perfect harmony. I began to move, spinning the spear swiftly around my body. The blades whirled close, but never once touched my skin. As the rhythm quickened, I could feel the energy flowing, my movements precise and lethal. Even a fly wouldn't stand a chance.

"Shadow Breathing: First Form," I murmured. Darkness swirled around me, enveloping me in an aura of shadow. My muscles twitched in response as I leapt into the air, twisting mid-flight and striking the nearest tree with a single, clean slash. Another strike followed in rapid succession, too fast for an opponent to counter.

Mastery of both hands was crucial—if I ever lost one in battle, I had to be able to rely on the other without hesitation. I continued to repeat the movements, testing both strength and speed. The shadows were my allies, making each attack invisible until the very last moment.

Four hours passed in a blur, and I finally paused, surveying the destruction around me. The trees were decimated, slashed and broken in every direction. I let out a sheepish laugh. "Oops."

The mask I wore during training always made me feel like a different person—a shadow that overtook my mind when the battle began. I wore a half-mask that covered only my mouth, unlike the full mask Urokodaki used. The full mask had been too cumbersome for me during training, hindering my performance.

I gazed up at the moon, feeling a calmness settle over me. Maybe it was time to call it a night. As I sheathed my spear, I stood still for a moment, taking in the peacefulness of the night. Just as I was about to leave, I heard the faint snap of a branch behind me.