Taisho Era – Year 2 (Early Spring 1913)
Location: Azabu-juban, Tokyo
The winter chill had reluctantly given way to the first hesitant breaths of spring in Azabu. The snow was gone, replaced by muddy streets and the promise of cherry blossoms yet to bloom.
One month had passed since Kai had established his footing in the world, one month of rigorous, secret training and surprisingly lucrative hustles. He'd moved from the streets to a small, dilapidated shack he rented from Old Man Sato using the only currency he had: favors and expertise.
'Great Sage, financial statement,' Kai thought, meticulously stirring a clay pot full of fragrant herbs over a small fire.
[Financial Status: 45 Yen, 34 Sen. Current income streams: 7. Primary source: Herbal medicine preparation. Secondary source: Culinary consulting for local eateries.]
'Not bad for a five-year-old,' Kai mused. 'Mitsuri would eat that much in a sitting, probably.'
His medical knowledge was proving to be a goldmine. The common cold, persistent coughs, minor infections—things that plagued the impoverished populace of Azabu—were easily cured with herbal remedies synthesized from his vast, downloaded database. He didn't cure everything; that would draw too much attention. Just enough to be known as 'Kai the little doctor.'
His cooking skills were equally valuable. He consulted for a local ramen shop, introducing subtle yet revolutionary flavor profiles that had people lining up around the block. He always insisted on working in the background, a silent culinary prodigy in oversized kimonos.
He was currently concocting a pain-relieving poultice for a rickshaw driver with a strained back. The smell of Angelica root and ginger filled his tiny shack.
"It smells... intense, Kai-kun."
Kai looked up. Mitsuri was standing in the doorway, bundled up in a new green haori that made her pink hair pop. Her cheeks were flushed, a basket full of freshly picked wild vegetables in her hands.
"Mitsuri-chan," Kai smiled, the sight of her immediately brightening his mood. "Come in, but mind the mortar and pestle. This stuff is powerful."
She stepped inside hesitantly, her eyes wide with curiosity. The shack was small but organized. Bundles of dried herbs hung from the ceiling; a small, well-used cooking area sat in one corner, and his makeshift 'clinic' in the other.
"You're amazing," she whispered, setting the basket down. "My mother used the salve you made for her headaches, and she says it's magic! It's all anyone talks about in the market."
"It's just science and a good memory," Kai dismissed casually, though he was secretly chuffed. "I'm earning enough to buy you all the mochi you can eat, someday soon."
Mitsuri giggled, her eyes sparkling. "You're still flirting with me, Kai-kun! You know, my parents are starting to worry that I'm spending too much time with a strange orphan boy."
"Am I strange?" Kai asked, pouring the finished poultice into a jar.
"Well, you talk like an old professor, you're the strongest person I know besides my father, and you make more money than most grown-ups in this neighborhood," she listed off on her fingers. "And your eyes... they're intense."
'The Yoriichi resemblance is a double-edged sword,' Kai thought. He capped the jar. "I'm just... motivated. The world out there is dangerous, Mitsuri. People get sick, people get hurt. I want to fix that."
He moved past the serious talk, adopting his usual charming persona. "Besides, you bring me these lovely greens. You're spoiling me."
"Oh! Right!" She pushed the basket toward him. "Mother taught me how to make ohitashi (blanched vegetables). She thought you might like some. It uses that recipe you told us about—the one with the subtle dashi."
"Excellent," Kai said, his eyes gleaming. He was cooking a meal with a future Hashira. Life was good.
They ate the simple but delicious meal outside, sitting on the step of his shack as the sun began to dip below the rooftops. The air was cool, but Kai's core temperature remained perfectly regulated thanks to his physique and his constant, low-level 'Total Concentration: Constant' breathing technique.
[Notice: 'Total Concentration: Constant' stamina efficiency has reached 88%.]
'Almost there. By the time I'm six, I'll be able to swing a sword non-stop for a full day,' Kai planned.
"Kai-kun," Mitsuri said quietly, breaking the silence. She looked serious now, staring at her hands. "Why are you so obsessed with strength? And doctors?"
He looked at her, seeing the nascent insecurities about her own monstrous, wonderful strength. He had to choose his words carefully.
"There are... monsters in the world, Mitsuri," he said, not directly mentioning demons yet.
"Things that hurt people. Things that take away families." He paused, thinking of his own 'background'—the orphan angle. "My parents were taken by something bad. I don't want anyone else to feel that empty feeling."
Mitsuri's eyes softened with profound empathy. She reached out and placed her hand over his small fist. The physical strength behind her touch was astonishing for a five-year-old.
"I understand," she said firmly. "I feel strong, too. Sometimes it scares me. I broke a plate last week just picking it up." She looked miserable.
"That's because the world around us is fragile, not because you are flawed," Kai said, turning his hand over and lacing their fingers together. His tone was gentle, reassuring.
"We live in a world made of weak clay, and we were made of iron. You just have to learn how to be gentle with the clay when you need to be. And strong as a mountain when the real monsters come."
Mitsuri stared at him, a profound realization dawning in her eyes. It was the first time anyone had validated her strength instead of fearing it.
"Iron," she repeated, a small, genuine smile forming. "I like that."
"Good," Kai squeezed her hand. "Now, I need to train. I have some 'chores' to do. Can I walk you home?"
He walked her back to the large Kanroji estate, the conversation turning back to light flirtation and childhood jokes. They parted ways at the gate, Mitsuri promising more vegetables tomorrow.
The sun was nearly gone when Kai returned to his shack. The moment he was alone, the childish demeanor dropped away, replaced by the intense focus of a man on a mission.
He walked to a secluded patch of forest just outside the main Azabu area, a place where he wouldn't be disturbed.
'Great Sage, initiate evening training protocol. 1,000 basic swings with the wooden bokken I carved. Focus on breath synchronization and form calibration for Sun Breathing. Medical archive download status?'
[Medical knowledge download complete. Culinary knowledge complete. Physical regimen beginning. Total Concentration: Constant is stable. Proceed with caution.]
Kai picked up his rough-hewn wooden sword. He stood in the fading light, the image of Yoriichi Tsugikuni flashing in his mind's eye.
He inhaled deeply, the air rushing into his lungs with a soundless efficiency that already surpassed normal humans.
One. The wooden sword whistled through the air, perfectly vertical.
Two. A horizontal sweep, precise and fluid.
He was a five-year-old orphan, a self-taught doctor, a culinary advisor, and a time-displaced soul with the potential of a god.
The world of Demon Slayer was a tragic play, but Kai was determined to rewrite the script.
Three.
He swung the sword again, the rhythm of his life falling into place. Money, skill, power, and protection—he was gathering it all, one steady breath at a time.