Since demons had a powerful group known as the Twelve Kizuki, further divided into Upper Rank and Lower Rank, each with distinct strengths and ranks, the Demon Slayer Corps also had hierarchies with differences in status and strength among its members.
Demon Slayers affiliated with the Demon Slayer Corps were generally classified into ten ranks—Kinoe, Kinoto, Hinoe, Hinoto, Tsuchinoe, Tsuchinoto, Kanoe, Kanoto, Mizunoe, and Mizunoto.
Kinoe was the highest, while Mizunoto was the lowest.
Generally, the higher the rank, the stronger they were, and the better their treatment, status, and authority within the Demon Slayer Corps. However, Kinoe was actually not the highest rank within the Corps.
The Demon Slayer Corps was led by a leader known as 'Master (Oyakata-sama)' and the nine strongest Demon Slayers known as 'Hashira (Pillar)'.
The Master was someone who led the entire Demon Slayer Corps, while the Hashira were nine highly respected swordsmen who supported the Corps, surpassing all other ranks within it.
Each Hashira was named after the breathing style they used.
For example, there were five fundamental breathing styles in this world—flame, water, wind, lightning, and stone. A Hashira who excelled in a particular breathing style would be named accordingly.
The Hashira who used Flame Breathing was called Flame Hashira, the Hashira who used Water Breathing was called Water Hashira, and so on.
Rengoku Kyoujurou, a Demon Slayer with a strong personality, was the Flame Hashira of the Demon Slayer Corps, one of the strongest swordsmen of this era.
At the same time, he stood as the most admirable and awe-inspiring swordsman, ready to confront an Upper Rank destined to arrive at this Mugen Train—a confrontation that would mark the end of his battle and his life.
Riezel cast his gaze upon the young man who illuminated the darkness around him like a flame.
"Hmm? What's up, Bento Boy!"
Kyoujurou, devouring his bento, oddly addressed Riezel with a peculiar nickname, perhaps noticing that Riezel's bento was from the same place as his.
"You're the one who looks more like a Bento Boy..." Riezel couldn't help but retort but decided not to dwell too much on the topic. "Well, since someone like you is on this train, it seems like this train is going to run into trouble soon, huh..."
Upon hearing that, Kyoujurou's bento-eating pace slowed down.
"Ahh, it seems you know a thing or two about us!" Kyoujurou nodded earnestly, his smile undiminished. "But don't worry! With me here, everything will be alright!"
Kyoujurou's words, spoken with such loud volume, attracted more attention than just a passing glance. Nevertheless, he didn't mind if others overheard, and neither did Riezel.
"This train is packed with two hundred people. Can you really handle all of them alone?" Riezel asked, continuing to munch on his bento while gazing ahead.
"Umu! You think it must be too tough for me?" Kyoujurou admitted calmly, without any hint of evasion.
Although he was a Hashira, one of the nine strongest Demon Slayers of this era, fighting demons while protecting two hundred lives was indeed no easy feat. If they were ordinary demons, it would be manageable since ordinary demons were no match for the Flame Hashira, as they were simply a matter of one slash. Even the Lower Ranks wouldn't stand a chance against a Hashira.
It was not strange since to become a Hashira in the Demon Slayer Corps, there were two requirements to fulfill.
One was to eliminate fifty demons and the other was to defeat a member of the Twelve Kizuki.
Consequently, most of the Hashira in the Demon Slayer Corps had personally defeated demons from the Twelve Kizuki. While they may have only defeated the Lower Ranks, it was enough to demonstrate their strength.
Regardless, the number of people missing on this Mugen Train had already exceeded forty. If they had all been eaten by a demon, then this demon involved must be far from ordinary.
Just as people gain nutrition from eating meat, demons also grow stronger and stronger from consuming humans. The more they ate, the stronger they became, and the more humans they could consume.
If an ordinary demon wanted to engage in mass consumption of humans, they might not be able to digest them all. This meant that since the Mugen Train had already 'consumed' over forty people, the demon on this train should be at least a Lower Rank due to this level of consumption.
While Kyoujurou may not fear a Lower Rank, protecting two hundred lives while fighting them was no simple task.
However, what if the demon on this train weren't a Lower Rank but an Upper Rank?
Not only were the Upper Ranks the strongest demons just beneath the Demon King, but their members hadn't changed at all in nearly a hundred years. They had never been defeated and had even killed many Hashira, proving their strength was far beyond that of the Lower Ranks.
If the Upper Ranks were to appear in Mugen Train, perhaps Kyoujurou's own survival would be in question, let alone protecting others.
However—
"Even so, I will fulfill my duty and not let a single person lose their life before me!" Kyoujurou crossed his arms and declared loudly toward the train's ceiling. "You can all rest assured!"
His statement startled all the passengers in the carriage.
In the eyes of others, Kyoujurou, who had been shouting and saying nonsensical things, seemed no different from a madman. Only Riezel could sense a strong and resolute determination in his seemingly loud words.
This young man truly thought like that, determined not to let anyone lose their life in front of him.
Even if the demon about to appear was an Upper Rank, he would fight to the end to protect everyone on this train. Those who felt the strength in his words would probably feel reassured, just as he said.
However, Riezel, looking at this young man, had a different thought.
"You're here to protect everyone, but who's here to protect you?" Riezel remarked casually, still munching on his bento.
A casual remark, yet it made even the Flame Hashira, who spoke so boldly, pause.
Kyoujurou didn't know that Riezel was also speaking from the heart.
After all, in the original work, although Kyoujurou did manage to keep all two hundred people on the train alive, in the end, he lost his own life.
Riezel genuinely admired Kyoujurou, hence why he said such a sentence.
Kyoujurou, for the first time, looked at Riezel, smiling at the youngster before him who was eating a bento just like him.
"Umu, the responsibility of the strong is to protect the weak, not to use the talents bestowed by heaven to harm others or enrich one's own pockets!"
Kyoujurou's voice was still loud, still powerful, but this time, his voice not only contained power but also conviction.
"Protecting everyone here is my responsibility!"
As for himself?
"Where there is a responsibility, there is belief! What does danger matter? Just stand tall and live with your head held high!"
Kyoujurou patted his chest and laughed heartily.
"Don't you dare underestimate me, Bento Boy, for my heart is ablaze!"
—Live with your head held high, set your heart ablaze.
This was the Flame Hashira, Rengoku Kyoujurou.
"..."
Riezel fell silent and didn't speak, only quietly finishing his bento, eating until the last bite. Finally, he placed the empty bento box down and, following the customs of this world, clasped his hands together.
*Clap*
"Thanks for the meal (Gochisousama deshita)."
In the next moment, Riezel turned his head and faced Kyoujurou.
"The responsibility of the strong is to protect the weak, you say?" Riezel stared directly at Kyoujurou's eyes, suddenly smiling. "If you say it like that, my responsibility is to protect you, isn't it?"
"What?" Kyoujurou was taken aback.
"Isn't it?" Riezel continued to smile. "After all, I'm stronger than you."
Even though his words were filled with unusual calmness and indifference, completely unlike Kyoujurou's loud and powerful tone, it was precisely these calm words that gave Kyoujurou an incredible sense of security.
"Stronger than... me...?"
Kyoujurou rarely murmured before revealing a big smile shortly afterward.
Like sunlight, like flames, a fierce and cheerful smile.
"What an incredible youngster!" Kyoujurou laughed heartily. "But unfortunately, I am a thousand times stronger than you imagine, so let me protect you!"
"No, no, no, I think I should be a hundred thousand times stronger than you imagine." Riezel said very earnestly, shaking his head. "So, let me protect you."
"Then I am a million times stronger than you imagine! Let me protect you!"
"Then I am ten million times stronger."
"Then I am a hundred million times!"
In the end, the two of them carried on with this bizarre argument in the quiet train carriage, leaving people dumbfounded yet with an inexplicable urge to smile.
As the argument progressed, a third voice suddenly burst in, overshadowing the two.
"This lord is a billion times stronger than you both! If you don't believe it, let's settle it once and for all!"
Accompanied by such a loud shout, a figure rushed extremely fast from behind the glass of the empty carriage door.
"Boar Rush!"
*BOOM!*
Shouting like this, the figure smashed through the carriage door, bringing countless wood chips with it and rushing into the spot where Riezel and Kyoujurou were.
"Stop it! You dumbass!"
"Calm down! Inosuke!"
Upon closer inspection, there were actually two people hanging on to this figure, looking like they were about to cry, but their efforts to stop the former were futile.
As for the one who crashed through the door, it was—someone with a boar head?
"Mwahahaha! Where's the Flame Hashira? Let's settle this once and for all!"
The boar-headed figure stood with hands on hips, laughing loudly.