In Demon Slayer With Heavenly Insight

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Chapter 32: Flame Breathing Ninth Form: Rengoku!

Kyojuro stood up, testing his legs. His movements felt natural, almost effortless. He jumped a few times, marveling at the absence of pain.

"No more pain," he muttered, surprised. "It's so smooth!"

Kanao's wide eyes widened even further, her heart brimming with shock.

Ren... is he really just a doctor? His skills are unbelievable!

Noticing her reaction, Kanoe's lips curled into a soft smile. She always enjoyed witnessing people's astonishment after being treated by Ren. The satisfaction he radiated when praised was even more rewarding to her than improving her swordsmanship.

"Thank you so much, Ren!" the Rengoku brothers exclaimed in unison.

Senjuro couldn't contain his joy. The leg pain that had plagued him for years was gone, just like that. He recalled when Ren had confidently wagered he'd defeat the Wind Hashira within half a month. Back then, Senjuro dismissed it as youthful bravado, a ploy to push himself.

But now?

Perhaps Ren really can achieve the impossible.

Faced with their gratitude, Ren smiled modestly. "It's no trouble. But, Brother Rengoku, I'll need you to visit the Butterfly Mansion for one more treatment to ensure complete recovery."

Senjuro immediately stepped forward, patting his chest. "Leave it to me, Brother Ren! I'll make sure my brother gets there!"

Kyojuro ruffled Senjuro's hair affectionately, but before anyone could say more, Ren spoke again.

"Actually, the root of the problem isn't just the injury. It stems from how Brother Rengoku uses his breathing technique."

"Huh?" Senjuro froze, unable to comprehend.

Ren's words challenged everything he believed. Their family's swordsmanship had been passed down for generations, honed to perfection. How could there be a flaw?

But Kyojuro, ever the scholar of his family's techniques, didn't dismiss Ren outright. He understood that all breathing forms originated from a singular source. Each had evolved to suit individual physiques and habits.

"If the breathing methods evolved, why couldn't there be room for further improvement?" he mused.

The brothers were engrossed in thought, and Kanoe also looked at Ren with anticipation.

"When you execute high-speed techniques, do you feel pain in your legs?" Ren asked Kyojuro directly.

Kyojuro hesitated before nodding. "Yes, particularly when using forms like 'Shiranui.' But I assumed it was simply a sign of strength."

Ren shook his head. "Pain is your body's alarm system. It's a warning that something isn't right. This isn't normal."

Senjuro interjected, "But... what if it's a hidden injury? Maybe the pain stems from an old wound left by a demon."

Ren smiled patiently. "Do you think there are demons—besides the Twelve Kizuki—that could injure a Hashira like Brother Rengoku to such an extent?"

The brothers exchanged glances, both realizing the improbability of such a scenario.

Ren continued, "That's why I believe this injury is self-inflicted—not deliberately, of course. The strain comes from improper technique."

Senjuro couldn't help but ask, "Is there a solution?"

"Yes," Ren replied. "But I'll need Brother Rengoku to demonstrate the Ninth Form of Flame Breathing."

Kyojuro's eyes narrowed. "The Ninth Form?"

Ren nodded. "Yes. I've already memorized the earlier forms you demonstrated. Now, I need to see the Ninth to pinpoint the issue."

Senjuro's skepticism resurfaced. "Memorized? All the forms? You mean..."

Ren interrupted by unsheathing his blade. With a swift, precise motion, he executed the First Form: Shiranui. A fiery arc illuminated the air.

Kyojuro and Senjuro gasped. Ren's movements were flawless—identical to their family's style. Yet, there was a subtle difference. Unlike Kyojuro, Ren didn't rely solely on his legs for explosive power. Instead, he utilized a high-speed vibration technique to achieve the same speed without overburdening his muscles.

"It's faster," Senjuro whispered, awe-struck.

The brothers were left speechless. Ren's mastery of their techniques after observing them only once was beyond comprehension.

Ren sheathed his blade, turning to Kyojuro. "So, Brother Rengoku, will you demonstrate the Ninth Form? With that, I can identify the root cause of your pain and help you adjust your breathing technique."

Kyojuro hesitated, his pride as a Hashira conflicting with his admiration for Ren's insight.

**