The atmosphere inside the Hashira meeting hall was unusually lively. Ubuyashiki Kagaya sat in his wheelchair, his pale face bright with a rare, gentle smile. His voice was soft but carried weight with every word.
"To slay the Upper Moon Six—with not a single casualty… This is the first time in the Demon Slayer Corps' hundred-year history that such a result has been achieved. You have created a new chapter of glory."
The gathered Hashira lifted their heads, all eyes turning toward Tomioka Giyu and Uzui Tengen.
The Stone Hashira, Himejima Gyomei, pressed his palms together and spoke in his deep, resonant tone. "Tomioka, Uzui, you've done well."
The Mist Hashira, Tokito Muichiro, remained silent as usual but gave a small nod, a rare flicker of approval in his eyes.
The Flower Hashira, Kocho Kanae, clapped softly, her smile filled with warmth.
"Of course we did!"
Uzui Tengen straightened his back proudly, tossing his silver-purple hair with exaggerated flair. "With my perfect rhythm technique and Tomioka's timing, taking down an Upper Moon Six was nothing difficult! But I'll admit, your synchronization was on point—you didn't drag me down for once."
Giyu, standing quietly beside him, simply nodded. "It was mainly your rhythm prediction that worked perfectly. Kanae's support on the perimeter, and To and Tanjiro's efforts to handle the rest of the district, made it possible. It wasn't my achievement alone."
He didn't mention the advance intelligence he'd gathered—he simply gave credit to the team, his tone calm and steady.
"You're always too humble," Kanae said with a light laugh, stepping forward to pat his shoulder. "You were the one who studied Daki and Gyutaro's weaknesses beforehand and built a detailed plan. Without that, we wouldn't have succeeded this smoothly."
Giyu opened his mouth, about to respond, but the meeting was already wrapping up.
Oyakata-sama gave final instructions for everyone to rest and recover, asked Tamayo and Shinobu to speed up their work on the antidote for Muzan, and then dismissed the group.
When they left the main hall, the warm light of early spring fell gently over the courtyard.
But instead of returning to his quarters, Giyu turned west—toward the secluded side of the headquarters.
Since Tamayo's laboratory had been established, Shinobu had practically lived there, working alongside Tamayo every day. It had been almost half a month since he'd last seen her.
The lab lay hidden deep within a bamboo grove. Yushiro had set up a Blood Demon Art barrier around the area, making it invisible to outsiders. From the outside, it looked like an ordinary patch of bamboo. Only the Kakushi with clearance could guide one to the entrance.
The Kakushi accompanying him lifted a woven vine curtain and whispered, "Tomioka-sama, please enter. Kocho-dono and Tamayo-dono are inside, developing the new compound."
Giyu nodded in thanks and stepped inside.
The interior was a wide stone chamber lined with shelves filled with bottles and flasks. The air carried a faint medicinal aroma—not sharp, but subtle.
Tamayo sat at a desk, holding a glass test tube, her focus unwavering as she examined the liquid inside. Yushiro stood beside her, jotting notes onto a clipboard.
Across the room, Kocho Shinobu sat at another table, pen in hand, sketching chemical diagrams and formula ratios. Her brow furrowed slightly, concentration etched into every movement.
She wore her Butterfly Estate uniform, the white fabric bright against her slender frame. Her hair was loosely tied back, with a few soft strands falling along her cheeks. Sunlight streamed through a small window above, casting a warm glow over her silhouette.
Giyu stopped at the doorway, silent, just watching her.
He watched the way she bit the pen gently while thinking. The way her wrist flicked swiftly across the paper as she wrote out complex equations. The way she brushed her bangs aside, her delicate wrist catching the light. He didn't even realize how long he had been standing there.
"Tomioka-san?"
It was Tamayo who noticed him first, her voice light and calm.
Shinobu looked up at once. Her eyes brightened in surprise before softening into recognition. "Tomioka-san? You're here? The Hashira meeting ended already?"
Giyu stepped forward, glancing at the papers on her desk—filled with formulas and dosage charts. "It just ended. Oyakata-sama asked me to check on your research progress and also…"
He hesitated, lowering his voice slightly.
"…to see you."
Shinobu's ears turned pink almost instantly. She ducked her head, pretending to rearrange the test tubes on her table. Her fingers fumbled slightly. "The research is going fine. Tamayo-san managed to extract an inhibitor compound from Muzan's cells. I'm working on refining the toxin to make it destroy demon cells faster."
Tamayo, noticing their exchange, smiled faintly. She glanced at Yushiro, and the two of them quietly stepped back, leaving the pair a bit of space.
Giyu moved closer to her desk and picked up one of the formula sheets, scanning it carefully. "If you add a trace amount of the modified wisteria extract here, wouldn't it increase the compound's stability? You mentioned before that the extract enhances cellular breakdown."
Shinobu blinked in surprise, then nodded slowly. "I did consider that… but the extract's toxicity is still too high. It can harm human cells if the ratio's not right. I'm still trying to balance it. Wait—you actually remembered I said that?"
"Yeah."
Giyu's answer was simple, quiet, but firm.
Giyu nodded naturally. "You mentioned it once before. You said that extract was the key, so I remembered."
Shinobu's heartbeat skipped. She looked up at him.
His expression was calm, but there was a faint, genuine focus in his eyes—he clearly wasn't saying it casually.
She quickly averted her gaze, reached for the water kettle beside her, and poured a cup of warm water.
"Here," she said, handing it to him. "You just finished the meeting, right? You must be thirsty."
As Giyu took the cup, his fingers brushed against hers. Both froze for a split second before quickly pulling their hands back.
He lowered his head to take a sip, hiding the slight warmth rising behind his calm face. Shinobu turned away, pretending to reach for a test tube, though she couldn't help stealing a glance at him from the corner of her eye. The corners of her lips curved upward without her noticing.
"You've… been staying up late again, haven't you?"
Shinobu blinked, startled by the sudden question. Giyu's gaze had drifted to the faint dark circles under her eyes.
"Your eyes look a little tired."
She stiffened, then replied in a small, guilty voice, "No… just been busy with research lately, that's all. Sometimes I go to bed late."
"No matter how busy you are, you still need to rest."
His tone was calm but carried an undertone of quiet concern. What he really meant was that if Kocho Shinobu overworked herself, the progress of the antidote research would slow—and that would affect their fight against Muzan.
"If your health collapses, that'll be a big problem for me."
The last line was soft, but every word reached her clearly.
Her face turned bright red in an instant, even her ears flushing pink. She spun toward him, eyes wide and flustered. "W–What did you just say?"
Giyu met her gaze, feeling his own heartbeat quicken, but he still repeated seriously, "I said I'll worry about you. You shouldn't ignore your own health."
The air inside the stone chamber seemed to warm immediately. Tamayo and Yushiro, sensing the mood, quietly moved to the far side of the lab, pretending to organize supplies while secretly watching them from the corner of their eyes.
Shinobu took a slow breath, trying to steady her voice. "I know… I'll take care of myself. You too. You've had a lot of missions lately, don't overdo it."
"Mm."
Giyu nodded, and a faint, almost invisible smile touched his lips.
"By the way, To mentioned that you taught him how to make basic toxins. He said he's mastered it and wants to ask you about more advanced formulas next time."
"Really?"
Shinobu's eyes brightened, her voice full of pride. "He learns quickly—very talented. Next time he visits, I'll teach him how to make composite toxins for Lower Moons."
They kept talking—about research progress, about To and Tanjiro's training, about the little things that happened during missions and daily life. Bit by bit, the tension melted away.
Sunlight filtered through the small window, spilling softly between them. The space that once felt distant now filled with quiet warmth and the faint pull of something unspoken.
"Oh, right."
Shinobu suddenly remembered something and took a small paper pouch from her pocket, holding it out to him. "This is a new lung-soothing medicine I made. You mentioned coughing sometimes during patrols. It dissolves in water—works better than the last one."
Giyu accepted it, their fingers brushing once again. "Thank you."
"No need to thank me… it's what I should do."
Her voice grew softer, but there was sincerity in every word. "If you ever feel unwell again, tell me. Don't try to handle it alone."
Giyu looked into her serious, gentle eyes and nodded. "Alright."
Even the faint scent of medicine in the room seemed sweeter now.
Tamayo glanced at them from the corner and smiled quietly, whispering to Yushiro, "It seems we'll need to give them a little more space from now on."
Yushiro nodded, his own lips curving slightly. "As you wish, Tamayo-sama. As long as I can stay by your side, I'm already content."
Giyu and Shinobu continued talking as sunlight slowly shifted, painting their silhouettes in a soft golden hue.
The glory of defeating an Upper Moon still lingered, the research to destroy Muzan pressed onward, and amid all the chaos and duty, this fragile, quiet warmth became their most precious comfort—
A promise that they would keep walking forward together, not only to defeat Muzan… but to protect the fragile light they had finally found.