As someone known by Tamayo to be exceptionally cowardly and afraid of death, Muzan had an immense obsession with immortality.
Muzan, the progenitor of demons, was born during the distant Heian period. Even before his birth, his heart had stopped beating in his mother's womb, and he came into the world stillborn.
Although he eventually survived, he was diagnosed with a terminal illness and was told he wouldn't live past twenty, always remaining bedridden.
Someone like him should have died a long, long time ago.
However, a doctor developed a medicine to extend his life, thus changing Muzan's fate.
Yes, Muzan was originally a human who could die and could get sick. It wasn't until after he took the medicine from that doctor that his body transformed.
He not only regained his health but also obtained eternal life and immense power.
From that moment on, the world saw the emergence of a new kind of monster—a demon.
With that, the so-called progenitor of demons was born this way.
As a result, in his search for immortality and perfect life, Muzan abandoned his family and original identity, wandering the world.
Tamayo became a demon was also because Muzan wanted to utilize her expertise in pharmacology to develop a drug that could overcome sunlight.
As someone familiar with the original work, Riezel naturally knew about Muzan's obsession with immortality and understood what he had been seeking in the world for a thousand years.
"Blue Spider Lily."
Riezel revealed the secret, known to very few.
"Kibutsuji Muzan researched the formula of the medicine made by that doctor and discovered that it was actually incomplete. It required a plant called 'Blue Spider Lily' to become a finished product."
Needless to say, Muzan had been searching for traces of the Blue Spider Lily all along to complete the unfinished medicine and become the ultimate immortal monster.
Knowing this fact, after Riezel beheaded the seven demons in the Ubuyashiki Estate, he whispered something into Gyokko's ear just before he turned to ash.
—Blue Spider Lily is in my hands.
Riezel was certain that these words had already reached Muzan's ears.
Muzan could give his blood to others, turning them into demons and thereby exerting complete control over them.
Those who became demons through his blood could not only have their minds read when near him but also have their directions and locations sensed. They could even engage in telepathic communication and share visions, allowing him to know everything happening to them to the greatest extent.
Although this control had its limitations such as decreased precision over long distances or reduced control when his own condition was poor, generally speaking, barring unforeseen circumstances, all demons were under his control, and he knew their every action.
Because of this, Riezel could confidently tell everyone.
"Kibutsuji Muzan definitely heard what I said back then..." Riezel stated calmly. "So, he will definitely come looking for me."
In the face of his obsession with immortality, Muzan, no matter how cowardly, wouldn't stay silent and hide again as he did hundreds of years ago.
He had been searching for the Blue Spider Lily since the Heian period, for over a thousand years, with no results. Now, with the sudden news of it, no matter what, he would go crazy for it.
Even if he feared and dreaded Riezel's strength, or was shocked that Riezel knew about the Blue Spider Lily, or even suspected a trap, he would still take action for immortality and a perfect life.
After all, this was his only obsession.
Riezel didn't believe Muzan could restrain his thousand-year obsession and hide without even attempting to confront him.
"You could say, from the moment I mentioned 'Blue Spider Lily' to the Upper Five, it was inevitable that Kibutsuji Muzan and I would face each other."
In a room covered with tatami mats, Riezel declared confidently in front of the higher-ups of the Demon Slayer Corps.
"Perhaps, it won't be long before we have a battle."
With those words coming out of Riezel's mouth, the room instantly fell silent.
Even Kagaya, along with everyone present, had their breaths slightly quickened in that instant.
No choice.
If all this was true, it meant one thing—the one they had always dreamed of finding and eliminating but could never locate was about to appear.
When that happened, as long as they killed him, all the demons in the world would perish.
No one would be eaten by demons anymore.
No one would suffer from the loss of their loved ones anymore.
No one would despair anymore.
No one would lose their happy lives anymore.
After all, each Hashira had, to some extent, lost their original lives and loved ones to demons. Naturally, this led them to harbor a deep-seated hatred toward demons, resenting them and desiring to exterminate every last one—especially Muzan.
Because of him, the demons that killed their loved ones existed in this world.
In other words, the tragedies in their lives were all caused by his actions.
With the imminent appearance of the culprit of everything, how could the Hashira remain calm?
At this moment, several astonishing auras filled the room.
One was surrounded by whirlwinds.
Another had flames igniting on his body.
Another had water flowing around his body.
Some caused anomalies in the atmosphere around them, with sounds like sonic booms or the shadow of a snake rising behind, looking particularly terrifying.
*Cough!* *Cough!*
Even Kagaya started coughing from his intense emotions, coughing so hard that blood dripped onto the tatami. In the next second, his wife and children panicked, hastily patting his back and feeding him medicine.
Riezel watched all this, furrowing his brows, not saying a word. Nonetheless, at this point, even if he didn't speak, no one present could ignore him.
"Is everything you said true?"
Sanemi stared at Riezel with bloodshot eyes, squeezing out the words through gritted teeth.
"Kibutsuji Muzan will come to find you? Are you absolutely sure?"
All the Hashira's gazes instantly focused on Riezel, filled with various intense emotions.
Riezel had expected the members of the Demon Slayer Corps to be excited if he told them about Muzan's matter, but he hadn't expected such a very strong reaction.
In fact, it was actually understandable.
After all, Riezel wasn't one of the Demon Slayer Corps, unlike these people who had experienced despair, pain, and the nightmare of having their loved ones taken by demons.
Even if he knew through the original work that the Hashira had various tragic pasts, knowing was one thing, understanding them was another.
In light of this, Riezel had to remind them.
"You all seem to think this is a good thing, but I don't." Riezel poured cold water on their excitement. "I won't comment on myself, but for you guys, if you face Kibutsuji Muzan, there's only one outcome, complete annihilation."
Evidently, this splash of cold water extinguished the intense emotions in the hearts of the Hashira. Only a few Hashira, who had very deep grudges against demons, were completely undeterred.
"As long as we can kill Kibutsuji Muzan, who cares about complete annihilation?!" Sanemi shouted. "Even if I die, I'll drag him to hell with me!"
"No, the problem is, I'm afraid you won't even be able to do that." Riezel said mercilessly. "You can't even defeat the Upper Ranks. Even if you all go together, without the Mark, without the Transparent World, without the Bright Red Nichirin Sword, you won't be able to hurt him at all."
"What did you say?!" Sanemi abruptly stood up.
Riezel glanced at Sanemi indifferently, then looked away, showing he didn't want to talk to him much.
Seeing this, Sanemi lost his temper.
"Sanemi!"
*Cough!*
Just as Sanemi was about to rush over and grab Riezel's collar, Kagaya spoke up in time.
"Don't be disrespectful to His Excellency. He saved me, saved the entire Ubuyashiki family, and saved the Corps."
Kagaya's simple sentence calmed Sanemi down.
At this moment, it was Obanai, who had also had conflicts with Riezel and had never been very friendly, who spoke up.
"What are these so-called Mark, Transparent World, and Bright Red Nichirin Sword you're talking about?"
His question successfully shifted everyone's attention to this topic.
"I remember, Tsugikuni mentioned these three names last time..." Shinobu suddenly brought up the topic.
"Ah, that's right!" Mitsuri also recalled it.
"So, what is it? It sounds pretty flamboyant to me." Tengen couldn't help but speak up.
Giyuu, Muichirou, Gyoumei, and Kyoujurou also showed expressions of interest.
Seeing their reactions, Riezel thought for a moment before deciding to explain.
"Well, it doesn't matter if I tell you..." Riezel crossed his hands over his chest. "The so-called Mark, Bright Red Nichirin Sword, and Transparent World refer to three types of ability."
"The Mark, also called the Demon Slayer Mark, is a veined mark that appears on the bodies of Demon Slayers, greatly enhancing their physical abilities."
"The Bright Red Nichirin Sword is an ability that significantly increases damage to demons, even reducing their regenerative abilities."
"The Transparent World is an ocular extrasensory perception that alters your vision, allowing you to perceive other living beings as if they were transparent. Once achieved, it maximizes perception, enables seeing through bodies, and significantly enhances movement speed, attack prediction, and reflexes."
Riezel explained calmly to everyone.
"These three abilities, if you manage to get one, can really boost your strength and make you a bigger threat to demons."
"If you have all three, you might stand a chance against an Upper Rank."
"In fact, even a low-ranking Demon Slayer with these three abilities could easily pose a threat to an Upper Rank."