In the original timeline, when the Flame Hashira Rengoku died, the Sound Hashira, Tengen Uzui, was away on a mission.
But since Chika had slept for nearly a month, she couldn't be sure whether the flamboyant ninja had returned or not. If he wasn't home… well, she'd just have to find another excuse to delay going back.
After all, she had zero intention of returning so soon. Sure, she felt a bit bad for Nezuko, but being used as a life-sized doll wasn't part of her bucket list.
As she wandered through the Demon Slayer Corps headquarters, deep in thought, she quickly realized another horrifying truth—
she was lost.
Utterly, hopelessly lost.
Eventually, after stumbling upon a fellow Corps member, she managed to get pointed in the right direction and finally arrived at the residence of the Sound Hashira, Tengen Uzui.
A former shinobi born into a clan of ninjas who'd survived the Edo era by hiding themselves, Tengen had grown up under the cold and merciless discipline of that world. Out of nine siblings, only he and his younger brother survived. Refusing to become another emotionless weapon, he left the clan behind.
By chance, he discovered the Demon Slayer Corps and, along with the three kunoichi he'd met during his ninja days—who later became his wives—devoted himself to slaying demons. Thanks to his exceptional physical conditioning and sharp instincts, Tengen quickly rose through the ranks to become the Sound Hashira.
Chika recalled all this as she approached his estate. Being the main Hashira of the Entertainment District arc, he'd left quite the impression.
If Rengoku was the "big brother" type, then Tengen was definitely the "cool older brother."
As she stepped into the courtyard, a deep, confident voice suddenly called out:
"Well, if it isn't the flashy girl Rengoku kept talking about. What brings you to my dazzling home?"
Chika spun around. Tengen stood casually against a wall, arms crossed, eyes gleaming beneath the jewels of his headband.
Nice. He's home.
Suppressing her excitement, she smiled lightly. "We're colleagues, right? We never really had the chance to get to know each other, so I figured I'd drop by."
Tengen smirked. "Lies. My flashy eyes can see right through you. You're terrible at lying, you know. Speak up—what do you really want? Sneaking around isn't very… flashy."
Chika froze, caught red-handed. He wasn't wrong. None of the Hashira believed she'd ever come just for small talk. They all knew her reputation.
Because Chika was, in short…
A training maniac.
After she proved that the Crimson Blade wasn't just a legend, every Hashira had started grip training in hopes of awakening their own.
But Chika didn't stop there.
While others were struggling just to activate their blades, she worked on reducing the activation time.
Rengoku could ignite his sword in three or four seconds—an impressive feat.
Chika, though? She'd pushed it down to just over one second.
She wasn't just training—she was evolving the concept of hard work itself.
So yeah… there was no way she'd just come here to "chat."
Awkwardly scratching her cheek, she decided there was no point pretending. "Actually… I heard you have a technique called Score. I'd like to learn it."
Tengen blinked, then chuckled. "Now that's more like it. Talking feelings ruins the mood anyway. Training, though—that's flashy."
He tilted his head, appraising her with a sharp, almost playful gaze.
Chika suddenly felt nervous. He's not going to say no, right? It's his signature move… but maybe he'll share it? Please share it…
"Tell me," Tengen said finally, "do you understand rhythm?"
"......"
Beads of cold sweat trickled down her face. Rhythm? Well… she'd played Rhythm Master as a kid… that counted for something, right? Maybe?
Tengen sighed loudly. "You don't need to answer. That face says it all. You don't even know a beat from a breath."
He crossed his arms. "This technique isn't simple. It's not just about fighting—it's about hearing the flow of combat itself. Without understanding rhythm, you'll have to start from scratch. It'll take time. And effort."
Chika nodded solemnly. She got it. Up until now, her training had been pure instinct—hit harder, move faster, train longer. But this… this would require study.
Was that discouraging? Maybe a little.
Would she give up? Not a chance.
Her eyes burned with renewed fire. "Please, teach me!"
Tengen smirked. "Since you're that determined… fine. Follow me."
He led her into his lavish home. Unlike her own simple quarters, his estate gleamed with luxurious decor—crystals, silks, and brilliant colors everywhere.
Even the walls looked expensive.
And yes, the presence of three women could be felt all around.
Chika couldn't help thinking, So these are the three wives, huh?
Not that she was judging him for that—it was just… uncanny.
Because his wives were basically gender-swapped versions of Tanjiro's team.
Hinatsuru — calm, brave, composed; basically female Tanjiro.
Makio — fiery and impatient; female Inosuke.
Suma — sweet, timid, and prone to tears; absolutely female Zenitsu.
Ufotable, you sly devils.
Before she could finish mentally laughing about it, Tengen stopped at a bookshelf, pulling out several large volumes.
"Catch," he said.
Whsh!Whsh!Whsh!
One. Two. Three—
Chika scrambled to catch them all, nearly toppling over. Each book landed heavily in her arms, and she stared at the titles with dawning horror.
Advanced Music Theory.
Combat Rhythm and Motion.
Frequency Analysis for the Skilled Swordsman.
They weren't manuals—they were textbooks.
For the first time in her life, Chika realized just how serious rhythm games could get.