Rengoku Shinjurou, the current "Flame Hashira," though now, that title has become a thing of the past.
He has retired.
Retiring before the age of thirty is quite rare. Thirty is supposed to be the prime of one's life. But reality is often cruel.
—He has lost the ability to fight.
Now, he often feels chest tightness, and even actively using Breathing Techniques causes sharp pain in his lungs. On ordinary days, he can't even lift heavy objects. Rengoku Shinjurou is, in a sense, broken.
Harsh as it may be, this is the nature of reality.
"At the very least, I am lucky."
Rengoku Shinjurou sat alone in his family's courtyard, muttering these words to himself.
He is still alive, able to watch his children and grandchildren grow. That, in itself, is a great fortune. Most Hashira of the Demon Slayer Corps meet their end in battle.
The Hashira are the foundation of the Demon Slayer Corps. When ordinary swordsmen cannot handle a demon, the Hashira step in. Even when ordinary swordsmen can handle a demon but at great cost, the Hashira still step in.
—Such is the fate of a swordsman.
"Father, how was my training?" The one asking was his eldest son, Rengoku Kyojurou, now thirteen years old.
Seeing him, Rengoku Shinjurou couldn't help but recall Li Mo's words before he left.
He said that Kyojurou was a genius. And in his eyes, Kyojurou would become the next Flame Hashira.
"Flame Hashira."
A title that the Rengoku family has held for generations.
"Kyojurou, you're doing very well."
Shinjurou's thoughts returned from the past to the present. He remembered Kyojurou's recent training. The boy had already mastered the first few forms of the Flame Breathing technique. He was only missing the latter half to fully master it.
—At Kyojurou's age, Shinjurou hadn't been able to achieve this level.
"Kyojurou, what do you think about Li Mo's disappearance?"
"If it's about my elder brother, then I believe he will return." Rengoku Kyojurou spoke with utmost sincerity.
It seemed he had never considered the possibility that the word "missing" might be a lie.
This child's way of thinking was entirely in line with the Rengoku family's values.
Just like how he used to be.
After walking through the gates of death, Rengoku Shinjurou found himself becoming much more indecisive.
"Father, when will Mother return?"
Kyojurou's voice brought Shinjurou back to the present.
Rengoku Ruka was not at home. She was currently at the Butterfly Mansion receiving treatment from a doctor named Tamayo from Tokyo. Before meeting her, Shinjurou had never imagined that this doctor would be a demon.
The Demon Slayer Corps cooperating with a demon? It sounded wrong, like a mistake. But after understanding the situation, he realized that this cooperation was necessary.
—All of it was for the sake of killing Kibutsuji Muzan.
"Ruka will return once she has fully recovered. In the meantime, Kyojurou, focus on your training. Once you've mastered all the forms, you can participate in the 'Final Selection.'"
"Yes, Father!"
...
Tomioka Giyuu and Sabito had recently risen several ranks in a short period.
Because they excelled at slaying demons, the two complemented each other perfectly. Their synergy allowed them to defeat demons far stronger than themselves.
One day, after slaying a demon in a mountain temple and resting, Sabito couldn't help but ask Giyuu, "Giyuu, what do you think about the news from our senior sister?"
After a long pause, Giyuu finally responded, "Hm?"
If Sabito hadn't grown up with Giyuu, he wouldn't have understood his response. He continued, "Do you think the information could be false? Disappearing in front of his comrades? What does that even mean? Could it be that our senior brother didn't die in battle?"
"It's true." Giyuu's response came a few beats later, as usual.
His way of speaking was always like this. Sabito would patiently wait every time he asked a question.
Hearing Giyuu's calm tone, Sabito couldn't help but smile. He placed his hands behind his head and said, "You're right. Our senior brother and sister wouldn't lie. Giyuu, how about we become Hashira before our senior brother returns?"
The night was quiet, with only the crackling of the fire breaking the silence.
...
Kumeno Masachika was an ordinary swordsman. At least, compared to that person, he considered himself ordinary.
That's what he believed.
But the little guy next to him didn't think so.
Shinazugawa Sanemi was a "rare blood."
"Rare blood" refers to individuals whose blood is irresistibly attractive to demons. When a demon consumes such a person, the effect is equivalent to consuming a hundred ordinary humans.
When Kumeno Masachika first met this white-haired boy, the latter used his "rare blood" to lure demons. The process involved drawing blood to attract demons, making them entranced in the scent, and then... defeating them.
This reminded Kumeno Masachika of the missing "Sun Hashira."
That man had slain demons even before joining the Demon Slayer Corps.
"Mr. Kumeno, you said someone killed a demon without being a rare blood or using a Nichirin Blade?"
"Of course, that person is the 'Sun Hashira.'"
"Oh, the missing Hashira? Missing? I think he's probably dead."
Then, Shinazugawa Sanemi got a light smack on the head from Kumeno Masachika. "The 'Sun Hashira' defeated an Upper Moon. That's the first Upper Moon to be defeated in a hundred years. Sanemi, how can you be so disrespectful?"
"Alright, alright. Once I pass the 'Final Selection,' I'll become a Hashira too."
Kumeno Masachika couldn't help but shake his head. As for the "Sun Hashira," he hoped the man was truly "missing," but his reason told him the man was likely dead.
As for Shinazugawa Sanemi's bold words, they might not just be empty boasts.
Kumeno Masachika looked at the boy, who was like a younger brother to him, and couldn't help but think.
...
...
At the Butterfly Mansion, in the medical room.
Tamayo walked out of the operating room, removing her surgical gown and gloves. Yushiro asked, "Lady Tamayo, how did the surgery go?"
"The surgery was successful. Yushiro, how is Miss Rengoku doing? Has her condition worsened after taking the medicine?"
Yushiro, the demon Tamayo had turned, was her assistant in medical research. But since coming to the Butterfly Mansion, her assistant duties had been taken over by Kochou Kanae.
"Miss Rengoku's condition hasn't worsened."
"That's good. She was a patient referred by Li Mo. It's great that we could cure her."
Tamayo spoke gently.
Yushiro fell silent at the mention of that man's name. The man who had so casually told Lady Tamayo, "You're beautiful."
Yushiro hated him, but he also deeply respected him. As a demon, he knew just how terrifying the Upper Moons were.
And that man had nearly single-handedly defeated an Upper Moon.
What a feat...
"Yushiro, come with me later for research. With the blood of the Upper Moon, we can make further breakthroughs in the medicine. I hope that by the time Li Mo returns, my poison will be complete."
"Lady Tamayo, do you really believe what Miss Kochou said?" Yushiro couldn't help but ask.
"Why wouldn't I? Yushiro, do you remember our first meeting with Li Mo? He was willing to trust me the moment he saw me—no, even before he saw me. If he really is from the future, then it makes sense."
Tamayo continued, "Besides, he is the successor of 'Sun Breathing.'"
"The successor of that man wouldn't die so easily."
...
A gear has disappeared, but it doesn't affect the operation of the Demon Slayer Corps' precise machine. In fact, after achieving the feat of "defeating an Upper Moon," the machine has gained even more vitality.
The destiny that has persisted for thousands of years finally has a glimmer of hope of being broken.
Everyone is working hard, anticipating, waiting for that moment to arrive.