Demon Slayer: Strength Gained with Every Swing of the Sword

Feng Yu sat on the bed, staring at Shinobu Kocho, who always wore a sweet smile on her face, and couldn't help but remember the prequel anime about her, Kanae, and Kanae's sister that he had watched in his past life.

This girl used her smile to cover the pain inside her heart.

She wasn't suited to be a Demon Slayer because her wrist strength was insufficient—she was the only one in the Demon Slayer Corps who couldn't decapitate a demon. But in order to avenge her sister, she found a different path, using her expertise in pharmacology and toxicology to develop poisons that could kill demons, compensating for her physical limitations.

She even created her own breathing technique—Breath of the Insect—making her both a genius and a tragic figure.

In the past, Shinobu Kocho was serious, stern, and straightforward, with a competitive and short-tempered side. After her sister, Kanae, passed away, Shinobu underwent a profound change. She began to imitate her sister's actions, speech, and personality, maintaining a composed demeanor, and started to smile at all times, just like Kanae.

When Shinobu Kocho was angry or serious, her face would become expressionless. In moments of rage, she would remind herself, "Being unable to control your emotions is a sign of immaturity." She would try to control her facial expression and calm down as much as possible.

At this moment, Feng Yu understood that Shinobu Kocho was attempting to inject poison into herself, hoping to die alongside Upper Rank Two, Doma, as a form of mutual destruction.

Feng Yu admired her courage but also thought she was foolish. Life holds hope, and even if that hope seems faint, one should learn to protect oneself first.

He understood why she had asked him to demonstrate two breathing techniques earlier—she wanted to become stronger, to increase her chances of defeating Doma in the future.

"No matter what, if we can reduce the tragedy even a little, it's better than nothing…" Feng Yu sighed as he walked toward the training square.

In the center of the square, Shinobu Kocho was already waiting for him.

"Feng Yu-kun, you're here…" Shinobu Kocho said, smiling.

"Shinobu…" Feng Yu responded.

"Feng Yu-kun, is there something you want to tell me?" Shinobu Kocho asked, her expression suddenly turning cold when she saw the hesitation on his face.

"No…" Feng Yu quickly denied, feeling a chill run down his spine when he saw her smile again.

"Then, Feng Yu-kun, tell me how you managed to master two breathing techniques," she asked.

"Actually… I don't really know why I can master two breathing techniques. It just came to me suddenly…" Feng Yu couldn't explain it clearly. Ultimately, it was because his body's recovery ability was so strong that he wasn't afraid of the irreversible damage caused by switching between breathing techniques.

"Maybe it's because of my physical constitution…" Feng Yu added.

"I see…" Shinobu Kocho observed Feng Yu thoughtfully.

"Feng Yu-kun, could you demonstrate your self-created breathing technique for me?" Shinobu Kocho requested.

"Sure!"

Feng Yu then began to demonstrate the two techniques of the Breath of Light for Shinobu Kocho.

"Total concentration, First Form of the Breath of Light: Moonlight Slash…"

"Second Form of the Breath of Light: Radiance Shining Across the World."

"These are the two techniques I've developed so far…"

Feng Yu finished the demonstration.

"Incredible, Feng Yu-kun! Your second technique actually made me feel the warmth of the sun…" Shinobu Kocho's face showed astonishment. "And this intense light might even surprise demons during battle!"

"Feng Yu-kun, can you demonstrate the transition from your Water Breathing to Light Breathing?" she asked eagerly.

"Mm, I can."

Feng Yu first used the Water Breathing technique, then switched to the Light Breathing technique.

The two techniques seamlessly transitioned.

Shinobu Kocho watched attentively, her smile gradually fading as her gaze remained fixed on Feng Yu's face.

"Hah~" Feng Yu exhaled after finishing the demonstration.

"Very impressive, Feng Yu-kun. None of us in the Demon Slayer Corps have been able to switch between breathing techniques without injury like you have," Shinobu Kocho praised.

"Feng Yu-kun, how does your body feel when you switch from Light Breathing?" she asked.

"How does it feel? Well… it feels a bit uncomfortable, and there's some damage to my body…" Feng Yu answered honestly.

Shinobu Kocho nodded in understanding. The Demon Slayer Corps had previously tested whether one person could learn and use more than one breathing technique, but it usually ended in failure. The greatest challenge was the discomfort.

Even the Hashira could learn two breathing techniques, but it didn't increase their power; in fact, it caused harm to their bodies. The Demon Slayer Corps focused on increasing strength, not weakening it.

Shinobu Kocho walked around Feng Yu, then suddenly drew a knife and lightly cut his skin.

"As expected…" Shinobu Kocho observed the cut as it quickly scabbed over and healed.

"Feng Yu-kun, it seems your body is quite unique…"

She couldn't resist touching the scab. As soon as she touched it, the scab fell off, revealing fresh skin without any trace of a wound.

"Feng Yu-kun, are you of rare blood?" Shinobu Kocho asked abruptly.

"Rare blood… I don't know…" Feng Yu pretended not to know whether he had rare blood, though his body was far more exceptional—he had an immortality-type constitution, which had an even stronger recovery ability than rare blood.

Moreover, before he acquired the immortality-type constitution, his recovery rate was already extraordinary, not to mention the various body-strengthening techniques he had.

If Shinobu Kocho hadn't let her guard down and slashed lightly, that wound wouldn't have been possible. With just that little strength, even a membrane wouldn't have been pierced.

Shinobu Kocho's eyes showed a hint of disappointment, but she still smiled.

"How about… you take a look at this?" Feng Yu, feeling guilty, took out a detoxifying pill from his system space and placed it in Shinobu Kocho's hand.

"Feng Yu-kun… What's this?" Shinobu Kocho looked at the small pill with confusion.

"If you take it, you'll know the effect… Just know that my body's strength is partly due to it…" Feng Yu didn't want to explain further.

With some doubt, Shinobu Kocho put the pill in her mouth.

"Numb… How can this woman still be so beautiful when she eats something?" Feng Yu turned his head away, not wanting to look at Shinobu Kocho.

"How is it possible!" Shinobu Kocho cried out in astonishment.

Her face immediately brightened with excitement, feeling her strength growing.

"Feng Yu-kun!" she exclaimed. "Where did you get this pill? Can you give me more? Or do you have the recipe for it?"

"This pill is called Detoxifying Pill… Where I got it is a secret. I don't have many left, but I can give you one more for research…" Feng Yu said.

"I see… That's a shame, but it's still very good…" Shinobu Kocho put the pill away, then noticed that Feng Yu had taken out two more Detoxifying Pills and handed them to her.

"You can take one more, and keep the other for research. I hope you can figure out its ingredients and mass-produce it," Feng Yu said without batting an eyelash.

"Feng Yu-kun, is this of the same quality as the healing pill Mr. Urokodaki gave me a year ago?"

"You mean the Healing Pill?" Feng Yu finally remembered that he had given Urokodaki a Healing Pill, but didn't realize he had passed it to Shinobu Kocho.

"It really came from you, Feng Yu-kun…" Shinobu Kocho said, smiling. "I must thank you deeply because of your Healing Pills, our Demon Slayer Corps has been able to reduce casualties."

"You mean the Healing Pill was successful?" Feng Yu asked, incredulously.

"Yes and no, Feng Yu-kun. We can only make a much weaker version of the pill. The main issue is that some of the ingredients seem to not exist in this world…" Shinobu Kocho said, looking at Feng Yu with a strange gaze.

"Feng Yu-kun, you're such a strange person…" she added. "You give off the feeling that you're someone who will sacrifice everything…"

Then, Shinobu Kocho took the Detoxifying Pills and left. She wanted to quickly research them and begin mass production.

After all, this pill was extraordinary. Her previously stagnant strength had noticeably increased, and the most surprising part was that her body had become so much cleaner.

"I wonder… If I can mass-produce it, will I be able to decapitate demons…" she thought as she left.

Feng Yu stood still, watching her leave...

"My secret cannot be told. I'm sorry..."

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