After breakfast, Yoriichi went through his usual daily training. Muzan suddenly remembered something as he lay in a rocking chair in the shade beneath the eaves, watching Yoriichi swing his bamboo sword at the wooden dummy Muzan had found for him.
"Yoriichi, how do you enter the Transparent World?"
"The Transparent World?" Yoriichi froze. How did Muzan know about that?
He had never mentioned it, had he?
But then he remembered how much Muzan knew, and the surprise faded.
"You can't enter the Transparent World?"
Muzan: (￣_￣|||)
What kind of humblebrag was that?!
Seeing his expression, Yoriichi had his answer.
"The Transparent World means having complete mastery over your body. You can seal off your 'Fighting Spirit'-something like killing intent-from the outside world, enter the selfless state, and push your perception to its absolute limit..."
Muzan nodded. Only after hearing Yoriichi explain exactly what the Transparent World was did he finally understand it.
Entering the Transparent World required enduring extreme pain, and desperate situations were often more likely to trigger it.
Of course, that excluded players with cheats. They were born with the Demon Slayer Mark and the Transparent World.
It was also more like the ultimate refinement of skill. You needed a powerful physique to attain the Transparent World.
Damn cheaters!
Muzan wasn't counting on finding himself in some desperate situation to unlock the Transparent World. He could only start practicing based on his own understanding.
Time passed quickly. While watching the two children grow up, Muzan kept trying to enter the Transparent World.
One day, Yoriichi asked Muzan to spar with him again.
Muzan had been watching Yoriichi's progress and had a good grasp of his strength.
He waited leisurely for Yoriichi to attack.
With a solemn expression, Yoriichi drew his sword, took a deep breath, then lunged forward, his blade slicing through the air as it came down.
At that moment, Muzan was dumbfounded.
His pupils contracted as he stared at the "special effects" playing out right before his eyes.
Sun Breathing?!
You've already got a Breathing Style at this point, you little bastard?!
Muzan hurriedly raised his sword to defend himself. A fiery heat washed over him, and the sunlight-like radiance made him uncomfortable.
Every slash Yoriichi delivered was swift and fierce. Shocked by the Breathing Style, Muzan instinctively unleashed his true strength.
At that instant, Yoriichi felt an utterly terrifying pressure. The presence of the man before him suddenly became unfamiliar.
Savage power and a vitality that seemed ready to devour everything bore down on the young Yoriichi, stopping his breath for an instant. In that instant, something seemed to pierce through his mind. His eyes widened, and his movements became incomparably fluid.
Realizing he had overreacted, Muzan hurriedly stepped back and pulled his sword away. But immediately afterward, he saw Yoriichi's scarlet blade trace a blazing circle like the sun as it slashed toward him.
Muzan's pupils contracted. An unprecedented sense of danger swept over him, and in an instant, he perceived the sword's trajectory and saw a different world.
He hastily dodged, barely avoiding Yoriichi's Sun Breathing, then stared blankly at the special effects surrounding Yoriichi's blade.
"Holy shit! Yoriichi! Are you trying to kill me?!"
That was the fucking Thirteenth Form of Sun Breathing!
How the fuck did he already have it?!
That was the thing that had nearly killed him in the original story!
Crack!
The blade struck the ground, gouging a deep dent into it. Yoriichi stopped moving and looked at Muzan, still shaken. What had he just done?
Muzan was still shaken too. Fuck, raising Yoriichi was way too dangerous!
Although Sun Breathing couldn't threaten him right now, Yoriichi already had both Sun Breathing and its Thirteenth Form. Would it really be surprising if he pulled out a Bright Red Blade next?
Muzan swallowed, put away his sword, and looked at Yoriichi, who was sitting on the ground.
"You scared the hell out of me. Next time you come up with something new, tell me before you try it out. That was way too damn dangerous. You nearly killed me..."
He still planned to live until the modern era and play around on a smartphone!
Sitting on the floor, Yoriichi nodded dazedly. The feeling Muzan had given him just now had been terrifying, as though a single touch would mean certain death. That fleeting danger had made him overreact as well.
"Ah..." Muzan sighed, walked over, and pulled Yoriichi to his feet. "Come on, get up. Don't sit there."
Yoriichi let himself be pulled up, nodded, and put away his sword.
Still, that brief instant had successfully scared Muzan half out of his wits-and into the Transparent World.
A fucking pleasant surprise wrapped in a heart attack!
It was worth mentioning that Yoriichi activated his Demon Slayer Mark every time they fought. His fiery red blade was genuinely intimidating.
As expected of a cheater.
Muzan went over and drank a few mouthfuls of water to calm his nerves before picking up his book again. But between the shock and the delight, all seven of his hearts were still pounding, and he couldn't focus on the book at all.
He had finally unlocked the Transparent World after decades of trying!
Although that moment had been dangerous, honestly, it couldn't have caused him any real harm anymore. As long as Yoriichi didn't use a Bright Red Blade, he wasn't in danger. At worst, he had gotten a fright, but the gains were enormous.
The Transparent World didn't strengthen the body. Rather, it represented a person's-or a demon's-absolute mastery of their body, perfect application of technique, and exceptional perception.
As one of the main ways Demon Slayers increased their combat strength in Demon Slayer, the Transparent World's ability to improve combat prowess was obvious.
Through the Transparent World, one could see an enemy's weaknesses while making one's own next move impossible to predict.
For Muzan, though, it wasn't much use for the time being.
After all, Yoriichi, the only person who posed a threat to him, was currently a little brat he was raising.
Still, Yoriichi had actually mastered a Breathing Style without him noticing, then created the Thirteenth Form in a single instant after Muzan provoked him.
That kid really knew how to keep things under wraps!
All he could say was that Yoriichi truly deserved his place at the very pinnacle.
Five years later,
The moonlight was gentle. A cool breeze rustled through the leaves, which swayed softly along with the shadows they cast by the window.
Muzan slept leisurely in his rocking chair. For a long-lived being like him, sleeping was probably the best way to pass the time.
Before long, however, the sound of Yoriichi pushing open the door woke him.
Removing the book covering his face, Muzan opened his eyes and looked at Yoriichi, who held a long sword.
The long sword in Yoriichi's hand was stained with half-dried blood. His expression was complicated, and claws had torn several gashes in his clothes. The young Yoriichi was breathing somewhat heavily, his face flushed and his sword hand trembling faintly.
Muzan's expression turned serious. "What happened?"
"I ran into a Half-Demon."
"?!" Muzan's eyes widened instantly. He tossed his book aside and stood up. "What happened?"
After learning that Yoriichi had already developed a Breathing Style, Muzan had openly told him that Nichirin Blades were the means of killing demons, and that Breathing Styles and Nichirin Blades complemented each other, allowing them to inflict greater damage on demons.
Over the past few months, Muzan had naturally told Yoriichi about Half-Demons as well. By the same principle, methods that worked against demons also worked against Half-Demons.
Although Yoriichi was still young, his skills were already enough to defeat ordinary Half-Demons and demons, so Muzan felt comfortable letting him roam around.
After all, he was still a child. Muzan couldn't keep him cooped up in this little place every day.
"I ran into a Half-Demon in the village up ahead, but I've already killed it."
Frowning, Muzan walked over and crouched to examine Yoriichi. Only after confirming that his clothes had merely been torn in a few places and that he wasn't injured did Muzan sigh in relief.
After all, this was a kid he had raised for years. As a father over five hundred years old, he couldn't help worrying.
Before you continue