33 Red blade

At Giyu's estate, Tomioka stood in his backyard, surrounded by a perfect circle of cuts and cracks painted on the ground. His sweaty figure reflected the intense training he'd been putting himself through.

The air was still; the soft rustle of the wind did little to cool his heated skin. His muscles bulged, veins popped on his forearms as he gripped his new blade with both hands, eyes narrowed in deep concentration. Yet, despite his best efforts, the results were frustratingly unsatisfying.

Giyu lowered his arms, letting out a heavy sigh of disappointment. During his battle with Upper Moon Two, his blade had turned red, becoming stronger and sharper than he'd ever felt it before. Now, he was trying to replicate that power, trying to unlock the same strength, but no matter how much he practiced, the blade refused to change again. He couldn't reach that state, no matter how hard he pushed himself.

It wasn't the first time he'd encountered a red blade. He remembered the final battle, clashing swords with Sanemi, or when Tanjiro had stabbed Muzan, the Demon King, in an effort to hold him still. In that fateful moment, Giyu had rushed to Tanjiro's side, helping him maintain his grip on the sword. Those were the first times Giyu had experienced the power of a red blade.

'How did you do it, Tanjiro?' Giyu thought, staring up at the sky. Doubt began to creep in. Was he too weak? Was his grip strength not enough? Perhaps his ability was simply lacking…

For a long time, Giyu stood there, thinking, his brow furrowed in contemplation, until an idea formed in his mind. Shinjuro Rengoku. Though now they barely acknowledged each other's presence and the Flame Hashira's disdain for him was evident, Giyu knew Shinjuro was a more experienced Hashira. Rengoku had a deep understanding of swordsmanship, and his flame breathing produced a blade that emitted a color similar to what Giyu had seen.

Despite their strained relationship, Giyu decided that Shinjuro might hold the answer to his problem. With a hesitant sigh, he left his estate, unsure of what to expect.

***

"What do you want? Get to the point," Shinjuro growled, his brows furrowed and fists clenched. The tension between them was palpable. Giyu's previous confrontation with him over Kyojuro still lingered in the air, and Shinjuro had not forgiven him. Yet, he couldn't entirely dismiss a slayer of Giyu's caliber. The Water Hashira's near victory over Upper Moon Two was no small feat.

"I need… your advice," Giyu murmured, his voice calm but resolute. "During the battle with Upper Moon Two, my blade turned red."

"A red blade..?" Shinjuro's expression shifted. His eyes, once filled with simmering resentment, widened slightly in realization.

Giyu continued, his frustration evident. "But after that battle, I've been unable to replicate it. No matter how much I try, I can't turn my blade red anymore."

Shinjuro remained silent for a moment, lost in thought. "A red blade," he repeated. "It is said that the Slayer Mark is required for your blade to turn red… but you…" Shinjuro's eyes fixed on the faint blue mark on Giyu's cheek. "That explains your strength. I was a fool not to realize it sooner, you've already unlocked the Slayer Mark. It looks so different from what's described in the books. I thought it was just a birthmark."

Giyu's hand instinctively moved to touch his cheek. He had unlocked his Slayer Mark at birth. Since then, the mark had rarely disappeared; each time his heart rate changed, it would appear again.

"It is said that any Slayer with a mark can access the power of the red blade. But the exact conditions to turn it red..." Shinjuro's tone grew more serious as he paused for a moment. "They're unknown," he finished, leaving Giyu in a disappointed silence, his eyes closing briefly as he processed the words.

"Except for the Rengoku family..." Shinjuro continued, catching Giyu's attention again. Giyu's eyes reopened, focusing intently on Shinjuro. "You mentioned before that you couldn't do it anymore, turning your blade red. That's because you weren't in the heat of a real battle. That changes everything. A swordsman's grip will always be firmer in the chaos of combat than in training." Giyu listened closely, absorbing every word.

"Strength and pressure are not the same thing," Shinjuro explained, his voice calm but filled with conviction. "Your blade won't turn red unless you truly need it to do so—when you're ready to give everything in the battle and then some more. The issue was never strength." He paused, raising his hand and pointing directly at Giyu. "The issue is you. Unless you pour your very heart and soul into that blade, it will never turn red again."

Silence hung in the air as Giyu processed Shinjuro's words. After a moment, he slowly stood up. "I'm very grateful for your teachings."

Shinjuro scoffed, turning away. "Don't thank me. You might actually be able to make a difference. That's the only reason I'm wasting my time with you."

Without another word, Giyu took his leave, the sound of Shinjuro's drink clinking against the cup the only noise breaking the tension.

***

Meanwhile, at the Butterfly Estate, Shinobu sat perched on the roof, her legs dangling over the edge as she stared out over the Slayer Corps. Her expression was blank, but her mind was racing with thoughts. It had been two days since her argument with Kanae, and they hadn't spoken since. The silence between them was unbearable, but Shinobu didn't know how to break it. She felt numb, her emotions locked away.

Her sister was the most important person in her life. Kanae was her family, the one who had always been there for her. Yet, that same person had called her weak and asked her to give up the life she had chosen to fight beside her. "I only wanted to be like you," she murmured before she clenched her small hand into a fist, a frown tugging at her lips.

She didn't want to cry, but Kanae's words weighed on her like a boulder, pressing down on her until she felt like she couldn't breathe. "Idiot sister!" she muttered, her voice shaking slightly.

Shinobu's gaze hardened as she made a choice. 'If I can't match a Hashira's strength, I'll make a poison so potent that it can kill a demon with a single stab.'