Chapter 159: The Boomerang Hits Back as Fast as a Tornado
Hearing the faint frustration and obvious grievance trembling in Kanao's usually quiet voice, Akira reached out, his hand gently resting on her head to comfort her. The motion was pure instinct, a protective reflex that moved far faster than his conscious thoughts.
It took a few seconds for the actual weight of her confession to penetrate his mind. His hand paused.
"Wait a minute," Akira said, his brow furrowing as he refocused on the glaring anomaly in her story. "The main point here is... you learned a Breathing Technique that long ago? And you did it just by sitting there and watching us for a little while?"
The special training Akira had put Kanae through naturally took place right after she survived the Final Selection. During those grueling afternoon sessions, Kanao had indeed been a constant presence. She would sit quietly at the edge of the sunlit courtyard, her small hands resting in her lap, her large, unblinking eyes tracking their every move.
But she hadn't even turned ten years old at the time.
, piecing together Kanao's quiet admission, she had originally aimed to learn Akira's own techniques. Only after mimicking him in secret and realizing her small frame couldn't handle the explosive burden did she pivot to studying Kanae's forms instead.
Even with that detour, for a child to reach a functional level of mastery in less than three months—purely through observation—was nothing short of terrifying.
"Mm..." Kanao offered a tiny nod. She didn't elaborate, simply tilting her head up to meet his gaze. Her lilac eyes were wide, clear, and unyielding.
In truth, the seed of this ambition had taken root in Kanao's heart much earlier than anyone realized.
It sprouted on the very night Akira had sent Kanae off to Urokodaki Sakonji to master Water Breathing. It was the same night Shinobu had finally dropped her prickly defenses and opened up to him. Back then, Kanao had stood in the background, painfully aware of her own helplessness, realizing the only thing she could offer was a quiet promise to be obedient.
But within the silent, simple landscape of the little girl's inner world, a new resolution had crystallized: she had to find a way to stand by Akira's side. She had to become useful.
From that day forward, Kanao turned her exceptional eyesight toward Akira's daily routines. She watched the way his muscles coiled, the rhythm of his lungs, the precise angles of his footwork, desperately trying to deconstruct his Thunder Breathing.
Unfortunately, the physical toll of Thunder Breathing was monstrous. Akira's movements were blindingly fast, a blur of golden electricity that defied tracking. Even with her innate, superhuman visual acuity, Kanao simply couldn't process the sheer velocity of his strikes, let alone replicate them with her fragile physique.
It wasn't until Kanae returned victorious from the Final Selection and began her intensive sparring sessions with Akira that Kanao found her opening. By quietly observing her older sister's more fluid, adaptable movements, Kanao finally grasped the foundational flow of a Breathing Technique.
Looking back, Akira couldn't help but marvel at the sheer, absurd concentration of talent among the women in his life.
Kanae had picked up Water Breathing simply by watching Makomo run through her drills.
Now, he was learning that Kanao had mastered the basics of a Breathing Technique just by sitting on the porch and watching Kanae.
Not too long ago, under Kanae's patient guidance and a sudden spark of personal inspiration, Mitsuri had successfully mutated Flame Breathing into her own entirely unique Love Breathing.
And even earlier than all of that, Shinobu had plunged into pharmaceutical research with such terrifying brilliance that she had essentially usurped Kochou Sawaki's position. The older man had been thoroughly demoted to running errands for the research team.
If Sawaki were here to defend himself, he would undoubtedly protest, grumbling that he at least organized the experimental data and handled the preliminary chemical preparations, while Yushiro was the actual errand boy.
As for Makomo? If she heard about this chain of effortless mimicry, she would probably draw her blade and threaten to fight these monstrously talented girls to the death out of pure, hard-working spite.
Yet, despite achieving an entry-level mastery of a Breathing Technique at such a tender age, Kanao had kept it completely hidden. She never swung a sword in public. She never breathed a word of it to a single soul.
She kept her silence because she understood the unspoken consensus shared by Akira, Kanae, Shinobu, and everyone else at the Butterfly Mansion: Kanao was meant to be sheltered. After surviving such horrific abuse in her early childhood, they all fiercely agreed that she deserved a safe, mundane life, far away from the blood-soaked reality of the Demon Slayer Corps.
She was simply too young. Kanao knew that if she voiced her desire to fight, it would be instantly shut down. Akira and her sisters would likely take turns lecturing her, wrapping her in soft, suffocating layers of concern until she abandoned the idea entirely.
If it were anyone else trying to stop her, Kanao could have hardened her heart and ignored them. But if Akira looked at her with those gentle, worried eyes and asked her to stop... she knew her resolve would crumble instantly.
So, she buried the secret deep and trained in the shadows.
To secure a private space to practice her forms, Kanao employed a quiet cunning. Though she had never once complained about the pungent smells or the late-night noises of Shinobu mixing medicines, she began to act excessively drowsy in the evenings. She would rub her eyes and pretend to be too embarrassed to fall asleep in the shared space, prompting a sympathetic Shinobu to arrange a separate, private bedroom just for her.
During the day, she used playtime with Nezuko as a cover, masking her physical conditioning as childish games of tag and imitation.
She even forced herself to spend less time clinging to Akira's side. Instead, she lingered around Kanae's solo training sessions, using the proximity to silently verify if her own hidden stances were correct.
This elaborate charade lasted until just moments ago, when Akira had softly told her, "Although I hate to see you get hurt, I respect your personal wishes more."
That single sentence was the key unlocking her cage. Only then did Kanao dare to lay her cards on the table.
She didn't voice the thought aloud, but the intense, unwavering light in her lilac eyes screamed her intentions: 'Brother said he would respect our personal wishes. He has to keep his word.'Akira felt a phantom arrow pierce his chest.'The boomerang really does come back as fast as a tornado.'
Suddenly, years of tiny, easily dismissed anomalies clicked into place inside his mind.
He remembered how Kanao would immediately dart into her private bedroom whenever she had a spare moment. He recalled how she would shadow Kanae whenever he and Kanae split up to train. He even remembered a casual comment Nezuko had made once, pouting about how Kanao never seemed to get tired during their games, despite Nezuko being a demon who regularly helped with heavy chores.
Kanao was always so quiet, so perfectly well-behaved, that everyone in the Butterfly Mansion had written off these quirks. They were just the harmless eccentricities of a healing child.
As a result, years had slipped by without a single person realizing that a prodigy was quietly sharpening her fangs in their own backyard.
At the very least, no one had bothered to warn Akira.
But realizing the truth now did him absolutely no good. The trap was already sprung.
Akira let out a slow breath. He lowered his stance, bringing himself to eye level with the young girl. His hands gently grasped her small shoulders, his gaze searching hers for any trace of hesitation. "Kanao... have you truly thought this through? You don't have to do this. You could have just—"
"I thought it through a very long time ago, Brother," Kanao interrupted. Her voice was soft, but it carried a weight of steel. "I want to be helpful. I want to be like my older sisters. I want to protect the things that matter."
The stubborn fire burning in her eyes refused to dim. Interrupting him was something the old Kanao could never have fathomed doing, but she had to do it now. She was terrified that if she let Akira speak, if she let him wrap her in his warm, protective logic, her iron will would melt away.
In Kanao's heart, Akira's safety and happiness eclipsed her own life.
"..."
Akira fell silent. He stared into Kanao's eyes, searching for a crack in her resolve, but found only an unbreakable mirror reflecting his own stubbornness.
Off to the side, Mitsuri had slapped both hands over her mouth. Her wide green eyes darted between the two of them, absolutely terrified of making a single sound that might shatter the heavy tension. She was completely holding her breath.
"Alright," Akira finally said, a small, helpless smile tugging at the corner of his lips. He nodded.
"Phew—"
"Phew—"
Two identical sighs of deep relief echoed through the courtyard at the exact same time.
One came from Kanao, the tension instantly draining from her small frame as she stood before Akira.
The other...
Akira and Kanao, their serious expressions instantly breaking, turned their heads in perfect unison. They stared at Mitsuri, who was currently bent over, blushing furiously and panting for air because she had held her breath for far too long.
Brother and sister blinked, their eyes filled with identical, utter confusion.
Then, their shared bewilderment melted into speechlessness, which quickly gave way to a mix of exasperation and warm amusement.
"I'm sorry..." Mitsuri squeaked, hiding her flushed face behind her hands.
Just like that, the heavy, suffocating atmosphere that had gripped the courtyard dissolved into nothingness, replaced by the gentle, familiar warmth of their chaotic little family.
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