Chapter 12

Set aside the notebook and pen, picked up the ordinary Nichirin Blade resting nearby—he now wanted to prove his guess from yesterday.

Is the condition for activating the Nichirin Blade truly based on grip strength?!

Gazing at the ordinary Nichirin Blade in hand, its exterior showed no difference from a standard tachi; he gripped the hilt and drew it from the scabbard.

Clang!

Holding the drawn Nichirin Blade, he examined it—it glinted faintly, no different from an ordinary weapon, with a slight chip on its edge.

“Let’s try!”

He gripped the ordinary Nichirin Blade tighter and tighter, yet still no change occurred.

“Did I guess wrong?”

“...No, perhaps my grip strength isn’t enough!”

He gripped the ordinary Nichirin Blade again, tendons bulging in his right hand—this time his strength was five to six times greater than before, yet the blade showed no change whatsoever…

“So I really was wrong…”

Suddenly, he felt the Nichirin Blade in his hand was different—the blade seemed warmer, faintly reddening.

“So my guess wasn’t wrong—it’s just that my strength isn’t enough!”

“Xiao Yue.”

“Understood, Master.” Xiao Yue and Zero shared perfect synergy; she understood what he needed, activated her calculation mode, and measured grip strength.

“Huh～” Zero took a deep breath, then gripped the Nichirin Blade again—tendons bulged once more, his strength even greater than before.

Xiao Yue’s eyes calculated the force changes:

【50 jūn… 200 jūn… 400 jūn…】

Grip strength increased with each attempt, finally stabilizing at around 700 jūn. (1 jūn ≈ 30 jin.)

Yet the Nichirin Blade’s blade only faintly reddened—it did not turn fully crimson.

“So my guess was right—it’s just that the strength isn’t enough! How much force is needed to turn the Nichirin Blade into a Crimson Blade?”

He turned his gaze to Xiao Yue and asked: “Xiao Yue, what was the force just now?”

“Master, the force reached 700 jūn, roughly equivalent to nearly 21,000 jin.”

“What?! Even that much force still isn’t enough to activate the Crimson Blade?!” Zero felt helpless—he had no idea how much strength was needed to activate the Crimson Blade and confirm his theory.

His mechanical left hand picked up the scabbard, preparing to return the Nichirin Blade—though frustrated, at least his hypothesis had been proven correct.

“If not for the dimensional suppression of my power, perhaps my full-strength self could have activated it! But even if I could, it would drain immense stamina and wrist strength…”

Just now, as Zero intensified his grip, he felt signs of fatigue in his stamina and wrists.

If this happened during battle, the enemy would seize the opportunity—he’d be left defenseless.

Just as he was about to sheath the blade and give up, he glanced at his mechanical left hand—a new idea emerged: “Maybe I can try this too!”

He gripped the Nichirin Blade’s hilt with his mechanical left hand, adjusted the auto-strength enhancement, and wanted to know: exactly how many jūn of force were needed to activate the Crimson Blade?!

【800 jūn… 900 jūn… 1000 jūn…】

When the mechanical left hand’s force reached around 1600 jūn, the Nichirin Blade in his hand turned fully crimson—he could feel the energy radiating from the blade, even sensing a faint, sunlike heat within it.

“About 1600 jūn of force… equivalent to 48,000 jin… meaning over 24 tons of force is needed to trigger the Crimson Blade?!”

Zero found this unbelievable—he now sensed the dimension he inhabited was far more complex than he’d imagined.

“Kyojuro Rengoku from centuries ago activated the Crimson Blade and crushed Muzan—how immense must his strength have been?!”

“No, it’s not that simple! He also had [Muzan’s Mark] and [Transparent World], plus his [Sun Breathing] and his Nichirin Blade—only together could he achieve it! After all, his Breathing Technique itself held immense power!”

After clarifying these points, Zero gradually understood just how powerful Kyojuro Rengoku was in this world—and how immense must Muzan’s strength have been as his opponent?

“Sigh… if I ever meet Muzan again, I’ll need to analyze him to understand his current power level.”

Ding! Clatter!

Zero hadn’t noticed his mechanical left hand still gripped the Nichirin Blade—he lost focus, and the blade shattered, leaving only the hilt in his hand.

Zero: (?_?)…

Xiao Yue: ?_?.…

Zero and Xiao Yue felt speechless—this ordinary Nichirin Blade… was of terrible quality!

He casually tossed the broken blade’s hilt aside as if nothing had happened.

...(＿＿)ノ｜

He gathered the shattered blade fragments, took out a piece of Bai Bu from his nanospace, wrapped them carefully, and set them aside—otherwise, if any resident of the mansion were cut by the shards, it would be a costly mistake.

On the notebook beside the word “Grip Strength,” he drew a line and wrote “1600 jūn grip strength,” then closed the notebook and pen and stored them in his nanospace.

Finally, he packed everything away into the nanospace, leaving only the sketch of Kyojuro Rengoku, the portrait given by Ubuyashiki Yoriichi, and… the low-quality fragments of the ordinary Nichirin Blade and its hilt.

Having finished, he lay on the tatami, staring at the ceiling, lost in thought.

“Master, shall we go to the library to search for information next?” Xiao Yue approached Zero, gazing at his face.

“Not yet. These are still just my guesses, but they’re sufficient for now—I’ll plan further later. Besides, we need to leave the Demon Slayer Corps first, explore, and learn more about this world.”

“Mm.”

As Zero considered his next move, he recalled the trial mentioned by Shinobu Kocho during his meeting with the Hashira.

“I wonder what this so-called trial is?”

After thinking a moment, he decided to ask Ubuyashiki Yoriichi directly—he was the head of the Demon Slayer Corps, so he’d know best.

At the door, he opened it and found Ubuyashiki Tane sitting in seiza beside it.

Ubuyashiki Tane, as yesterday, followed Ubuyashiki Yoriichi’s orders and waited here to assist Zero if needed.

“Lady Tane, I wish to see the Head. Please guide me there.”

“Yes, Lord Zero.”

Led by Ubuyashiki Tane, he entered the inner chamber and found Ubuyashiki Yoriichi seated on a cushion; behind him sat two girls, also in seiza: Ubuyashiki Hina and Ubuyashiki Hina.

A table stood before them, with three teacups and some snacks arranged neatly.

“Zero, you’ve come. Please sit.”

Zero sat on the cushion opposite Ubuyashiki Yoriichi; Xiao Yue perched on his shoulder.

He noticed the tea on the table was still warm.

Clearly prepared before his arrival—though he didn’t understand why, it didn’t matter.

The tea leaves floated upright in the cup; he lifted it and took a small sip.

“The tea tastes good. Did you know I was coming to see you?”

“No. Just instinct.”

“I see…” Zero wasn’t surprised by Ubuyashiki Yoriichi’s answer—only curious.

“Then, Zero, what brings you here?”

“There are two matters.” He set the teacup down and raised the question about the trial.

Ubuyashiki Yoriichi then explained the nature of the trial to Zero.

The trial, held annually at Mount Riluoxi, is unique—the mountain blooms with purple wisteria year-round.

Demons detest purple wisteria; many demons are imprisoned on this mountain, and the wisteria vines restrain their movement.

But halfway up the mountain, the wisteria ceases to bloom—and that is where the trial begins.

The demons within Mount Riluoxi are mostly low-grade demons captured by Demon Slayer Corps swordsmen—sufficient for the trial.

Even if all demons are eliminated, new ones are placed there to prepare for future trials.

The final selection task is simple yet brutal: participants must slay demons within Mount Riluoxi and survive seven days to pass the trial and become Demon Slayer Corps swordsmen…

Hearing Ubuyashiki Yoriichi’s explanation, Zero now understood the trial—and formed his own theories.

Yet during the explanation, he noticed several flaws in the trial.

“About the trial, I have several questions.”

“Speak.”

“First: if a candidate entering Mount Riluoxi hides in a safe spot and simply waits out the seven days, does that count as passing the trial or not?”

Ubuyashiki Yoriichi knew this question well—the Kiri no Kuro had reported such cases; some Demon Slayer Corps members had indeed done this.

But rules were rules—anyone who passed the trial became a swordsmen.

Zero saw the answer in Ubuyashiki Yoriichi’s eyes and sighed slightly.

“Rules are rigid; people are adaptable! No rules, no order—but rigidly clinging to them isn’t always wise. Sometimes, rules can—and should—be broken.”

“Then what is your suggestion?”

“My suggestion is simple: assign several Gao Jie swordsmen to secretly monitor the trial participants—do not intervene unless absolutely necessary.”

Zero then explained his proposal: if any trial participant faced mortal danger, the hidden Gao Jie swordsmen could rescue them.

But they would forfeit their chance in this trial and must wait for the next one.

This would preserve their lives while giving them time to grow stronger before the next trial.

As for those who merely hid to pass the seven days, issue a warning.

Hearing this, Ubuyashiki Yoriichi understood its significance.

Indeed, if trial participants died, the loss was too great—they were all living souls.

But if Zero’s method were adopted, though more complicated, those who passed would become elite Demon Slayer Corps swordsmen.

Ubuyashiki Yoriichi: “And your second question?”

“Second: can you guarantee these captured demons have no other hidden conditions?”

“Why say that?” Ubuyashiki Yoriichi asked.

Zero then explained his views on the Mount Riluoxi trial and his earlier theories.

The Fujibayashi Mountain evaluation is held once a year, and those captured low-grade demons become stepping stones for those seeking to join the Demon Slayer Corps.

But what if some of these captured low-grade demons have other circumstances? For example: mutation?

The captured low-grade demons are imprisoned within Fujibayashi Mountain, unable to escape, and those participating in the evaluation naturally become their food.

But if the evaluation has not yet begun, and the demons in Fujibayashi Mountain have no source of food, what then?

Perhaps they will wait for the sun to rise and commit suicide, or, in extreme hunger, resort to cannibalism!

Of course, another possibility exists: devouring the human evaluators, hiding afterward to grow stronger, then emerging again when the next evaluation arrives to devour the new participants, and so on.

“These are my thoughts—what do you think, my lord?”

Zero’s words plunged Ubuyashiki Yōya into deep thought; indeed, it’s not the ten thousand possibilities that frighten you, but the one in a million—anything could happen.

“My suggestion is to regularly send high-rank swordsmen or Pillar-level swordsmen to inspect the situation. Though inconvenient, it’s always best to be prepared for anything,” Zero proposed.

Ubuyashiki Yōya pondered, agreeing Zero was right—this approach was certainly acceptable.

“Thank you, Zero!”

“You’re welcome. Now, one final question: what happens to the swordsmen who fail the Fujibayashi Mountain evaluation?”

Zero had pondered this question himself before asking it. Now, it was only speculation—he knew it might sound harsh, but lives are only lived once.

Ubuyashiki Yōya merely smiled at Zero, neither confirming nor denying. Zero already knew the answer; for some reason, he felt a quiet ache in his chest.

Though these people had no connection to him, they were still living, breathing souls.

As if sensing Zero’s sorrow, Ubuyashiki Yōya spoke: “I’m sorry, Zero. This is the evaluation. Seeing those children die breaks my heart—if I could, I would gladly die in their place…”

Before he could finish, Zero raised his hand to stop him—he understood: Ubuyashiki Yōya truly saw these people as his own children.

Otherwise, none of the Demon Slayer Corps’ combatants or support staff would hold him in such reverence and affection.

Moreover, Ubuyashiki Yōya remembered every fallen swordsman’s past and name.

“Master.” Xiao Yue sensed Zero’s emotional shift and reached out to stroke his cheek.

“I’m fine, Xiao Yue. Don’t worry!”

“Huh…” Zero took a deep breath to calm himself. “Forgive me—I was impolite.”

“It’s alright. I can see you’re someone who fears no hardship for others’ sake. I feel you’ve endured far more than any of us.”

These words reminded Zero of the days he fought the other nine Time Patrol Officers—how Number One always scolded him for never valuing himself.

He always charged ahead first, no matter the danger, and after every mission, vanished alone.

The other nine Time Patrol Officers had all watched this, knowing Zero’s past—but he himself seemed to have forgotten it all, even his own name.

He often muttered, “Being alone is fine.”

“Zero, you said there were two things—what’s the second?”

“The second: I want to know if anyone in the current Demon Slayer Corps still uses the Original Breathing Style—Sun Breathing or Moon Breathing?”

After careful thought, Ubuyashiki Yōya answered: “No. All current Breathing Styles are derived from the five major styles that branched from the Original. Moon Breathing has never been heard of, nor seen.”

“I see…” Though he didn’t get the answer he wanted, Zero still held to his original suspicion.

Just as Zero rose to take his leave, Ubuyashiki Yōya spoke: “Zero, I have a favor to ask of you.”

“Say it—anything within my power, I’ll do.”

“I’d like you to serve as an examiner for the Fujibayashi Mountain evaluation in three days.”

Zero thought for a moment and agreed—even if Ubuyashiki Yōya hadn’t asked, Zero himself wanted to see what the evaluation was truly like.

Besides, you don’t refuse a favor when you’re eating their food and sleeping under their roof. As a member of the Demon Slayer Corps, refusing such a small request would be rude.

“Alright, I’ll be there in three days. By the way, where is the Fujibayashi Mountain evaluation held?”

He knew of the evaluation, but not its location—if he went and couldn’t find it, it would be embarrassing.

“The Kuchisake Crow will guide you to the site.”

“Kuchisake Crow?” Zero knew what it was—he’d checked its data with his Analytical Glasses before.

The Kuchisake Crow is a crow used by Demon Slayer Corps members to communicate with headquarters; each member has one, transmitting real-time updates.

Though all Kuchisake Crows look similar, their personalities differ.

Ubuyashiki Yōya nodded to Ubuyashiki Hikaru, who rose and walked to the door, clapping her hands. A crow flew in from afar and landed on the wooden plank beside her feet.

But this crow was unlike the others—it was entirely snow-white.

Zero grew curious: why was this crow different? He used his Analytical Glasses to find out.

【Albino Kuchisake Crow】

【Gender: Female】

【Order: Corvidae】

【Genus: Corvus】

【Class: Aves】

【Description: This is an albino Kuchisake Crow. Aside from its feather color, it is identical in essence to other crows.】

“So it’s just albinism… but it does look quite adorable.” Thinking this, Zero rose and walked to the albino crow, picking it up.

Yet the crow seemed somewhat insecure—Zero had already guessed why.

He suspected the albino crow, due to its unusual feather color, felt out of place among the others, leading to few companions willing to speak with it—hence its withdrawn nature.

Ubuyashiki Yōya’s next words confirmed his guess.

“Zero, this crow, due to its condition, has been shunned by the others. But it’s truly a good child—I hope you two can get along.”

“Yes, I will. This crow is quite lovely—I like it very much. Thank you, my lord.”

Looking at the crow in his arms, Zero thought a moment, then said: “Snow-white feathers, like snow—you’ll be called Snow. I’m Zero, and this is my sister, Xiao Yue.”

Upon hearing this, Snow’s eyes flickered with emotion. She had braced herself for rejection by this Pillar, fearing she’d be denied as a liaison.

Among the crows, she often lived alone; few companions ever spoke to her.

Even when she tried to initiate conversation, she was brushed off with a few cold words.

Only yesterday did Ubuyashiki Yōya come to the crow’s roost and ask if she’d like to serve as liaison to a new Pillar.

She had no real hope—she came only to try.

But now, hearing someone wanted to befriend her—and even gave her a name—her heart swelled with joy.

“Zero-sama, Xiao Yue-sama, please guide me!” Snow’s voice was crisp and pleasant.

Zero: “Xiao Yue, now you have a new companion!”

Xiao Yue: “Mm-hmm!”

Looking at the crow in his arms, Zero stroked its head and smiled: “Snow, in three days, guide me to the Fujibayashi Mountain evaluation site. For now, go play with Xiao Yue—I have other matters to attend to.”

Xiao Yue/Snow: “Yes.”

Thus, Xiao Yue and Snow played together in the courtyard, their laughter bright and cheerful.

“Zero, I leave the rest to you. Also, your residence will be completed in two days.”

“Thank you, my lord. I’ll take my leave now.”

After bidding farewell to the Ubuyashiki family, Zero returned to Chochiya.

In Chochiya’s courtyard, he took out pen and notebook, reorganizing all gathered information. When done, he closed the book and returned it to his Nanospace.

He looked up at the sky, unsure what to do next, so he simply connected his Analytical Glasses to the Nanospace projection to check for any overlooked weapons or items.

“Huh? What’s this?”

Through the projection, Zero saw three other items in his Nanospace: a black launcher, a black motorcycle, and a black armored vehicle.

They had been hidden behind the towering form of the Dark Alloy Battle Armor, so he hadn’t noticed them before.

“Wait—when did I even make these two vehicles? Let me retrieve them.”

A ripple in the air appeared around the open ground before him, and a sleek black motorcycle materialized.

It was two meters long, one meter high, weighing 800 jin, with two four-barrel rotary machine guns mounted on each front side.

Entirely black, adorned with faint crimson glowing patterns.

Zero immediately scanned the motorcycle with his Analytical Glasses.

【Name: Dark Alloy Battlefield Motorcycle】

【Weapon: Four-barrel High-Rate Machine Guns】

【Description: This motorcycle was constructed by Zero over one year, before becoming a Time Patrol Officer candidate. It adapts to nearly all harsh environments and, equipped with four-barrel high-rate machine guns, inflicts heavy damage on monsters. With energy crystals installed, it can sustain prolonged travel and combat.】

“??? ” Zero’s head filled with question marks—he had no memory of building this.

“How many weapons did I even make…? But it’s not a bad thing—at least, in this world, these weapons give me and Xiao Yue enough means to defend ourselves!”

“Though the interface suppresses my power, these weapons are enough!”

Having clarified his thoughts, Zero returned the Dark Alloy Battlefield Motorcycle to his Nanospace and retrieved the black launcher.

【Name: Dark Alloy Missile Launcher】

【Ammunition Capacity: 10 rounds】

【Description: This was casually crafted by Zero during idle moments. Each missile inflicts heavy damage within a two-meter radius. Inserting an Ice Energy Crystal freezes enemies, restricting movement. Inserting a Red Energy Crystal causes sustained burning!】

“(ー_ー)!! …Calmly made during idle moments… How bored was I back then to casually make this?”

“Better not use this. Killing demons is one thing—but accidentally blowing up ordinary people or innocent animals? Too costly. Or worse—a fire…”

Zero returned the Dark Alloy Missile Launcher to his Nanospace and retrieved the black armored vehicle.

Boom!

A surge of spatial distortion, and a massive white armored vehicle crashed heavily into Chochiya’s courtyard.

Zero analyzed the vehicle’s data with his Analytical Glasses…