Shinobu clenched her small pink fist, smiling through gritted teeth.
"Lock, why are you dodging so fast? I'm not going to eat you, you know."
Lock didn't look convinced in the slightest. His tone was calm but serious.
"Hard to say. I heard some people can eat demons in this world—so who knows what else they might try to eat."
Shinobu's expression darkened instantly, a vein pulsing on her temple.
She reached for her sword—but Lock lightly pressed down on her hand, stopping her before she could unsheath it.
"You really—" she began, biting back the rest of the sentence. The words 'bullying me' nearly slipped out, but she swallowed them. A Hashira couldn't exactly complain like that.
Still, Lock was definitely getting bolder.
Just yesterday, she'd spent the entire day passing down her footwork and insect-style principles.
And now, the same boy was using them to tease her?
Very well, she thought, inhaling deeply. A sharp gust filled her lungs as she prepared to teach him a lesson—
But at that exact moment, a crow swooped down into the courtyard.
"Caw! Message! Traces of a demon sighted in Mount Akitake! Strong presence detected—summoning Shinobu Kocho immediately!"
The repeated cawing echoed through the Butterfly Mansion, halting her entirely.
Lock smiled slightly. "Looks like something's come up."
"The mission is important, isn't it? You should go," he said lightly, pretending to sound thoughtful—though Shinobu could clearly see the teasing glint in his eyes.
Her jaw tightened. "Train well while I'm gone," she said firmly.
"Got it, got it," Lock replied, raising his hands in mock surrender.
Shinobu quickly gave Aoi and Kanao a few instructions, then disappeared into the house to prepare for the mission. Moments later, she leapt into the fading daylight, her silhouette vanishing beyond the walls.
Lock's expression shifted—his usual humor giving way to a quiet seriousness.
He turned toward Aoi and the younger attendants. "Is she always this busy?"
"Yes," said Aoi matter-of-factly. "Shinobu goes out on missions almost every day. The number of demons hasn't dropped, even with the Corps working nonstop."
Another attendant added softly, "She works really hard. Ever since Miss Kanae passed, Shinobu's been managing everything here alone."
"But she never complains," another chimed in. "She always smiles for us. Like she's… trying to make it easy for everyone else."
Lock nodded slowly.
She's only eighteen… and yet she carries so much.
He'd seen the warmth she brought to the Butterfly Mansion—the calm, the kindness, the laughter. She hid her exhaustion behind a gentle smile, but now that he'd seen how much she bore alone, Lock couldn't help but feel a little ashamed.
He'd been training, yes—but not with the same resolve.
That night, as the sun dipped below the mountains, he began practicing with Kanao again. Together, they ran through the patterns of Flower Breathing until he could perform every form seamlessly.
The days passed quickly.
Only a week remained before his match with Sanemi.
Lock reviewed everything he had learned. His body had grown noticeably stronger—his stamina greater, his movement sharper.
He'd incorporated modern physical training methods: weighted running, push-ups, squats, sit-ups—relentless, daily routines. By the fourth day, he could feel the difference. His recovery rate had improved, and his lungs felt powerful, capable of handling far greater pressure during breathing forms.
Then came the breathing itself.
Lock pushed his body with fast, deep breathing through the day, then practiced slow, controlled breathing at night—steady enough to make air flow through every vein, down to his fingertips.
He began meditating regularly.
Through meditation, Lock discovered something unexpected.
He could consciously enter a strange, heightened state—a slowed perception where the world itself seemed to move in slow motion. Every sound, every twitch, every breath around him became clear.
He called this state "Bullet Time."
In that state, Lock's awareness expanded beyond normal limits—his focus sharpened until even the smallest details stood out. Like the compound eyes of an insect, he could perceive multiple movements at once.
But it came at a cost. Overusing his mind left him drained, his body fatigued.
So he learned to balance it—splitting his focus, alternating between deep learning and physical recovery.
Days blurred together.
No new techniques emerged during that time, but Lock refined everything he had—draining every muscle and fiber of his being to grow stronger.
Five days before the duel, Shinobu still hadn't returned from her mission.
The medical ward had grown busier, forcing Lock to assist Aoi with treating the wounded.
He quickly earned a reputation.
His precision, calmness, and intuitive grasp of medicine shocked everyone. Even the most severe wounds seemed to heal under his care. Soon, rumors spread among the Demon Slayers—
"There's a miracle doctor at the Butterfly Mansion."
Lock, of course, downplayed it. "I'm just helping. Anyone could learn this if they paid attention."
"Lock," Aoi called from the next room, "can you grab some fresh bandages from the basement? We're out again."
"On it," Lock replied, brushing off his hands and heading down the corridor.
The basement was dim and quiet. He searched the shelves, but instead of bandages, his eyes caught something else—an open door to a small, neat laboratory.
Curiosity tugged at him.
The room was filled with vials, tools, and handwritten notes in elegant script. On the desk lay several documents covered in meticulous annotations and sketches. Despite the clutter of research, everything was clean—orderly, like the person who worked here.
Lock's gaze fell on a small notebook left near the edge of the desk.
The ink on the cover had dried; it must have been written only a few days ago.
It looked like a diary. Shinobu's diary.
He hesitated, then carefully opened it.
On the first page, neat handwriting greeted him:
"Tuesday. Weather: sunny."