Ten days later.
Bang! Bang! Bang!
With flushed faces and desperate effort, Tanjiro, Zenitsu, and Inosuke each blew apart a massive gourd in succession.
This was the final lesson of Total Concentration: Constant. Being able to do this meant their physical condition had improved tremendously.
"Congratulations. It looks like you've fully recovered."
Asuka stood not far away and said to Tanjiro and the others, "Since your bodies are fine now, we depart today."
"Depart? Where are we going?"
"Whaaaat! We're already going on a mission? I suddenly feel a little dizzy..."
"Gahaha! Finally getting out of this nest! I'm gonna cause some chaos!"
Last night, Asuka had been learning simple and efficient medical first aid from Shinobu Kocho, as well as how to use Breathing Techniques more effectively to stop ruptured blood vessels inside the body.
Caw!
A Kasugai Crow fluttered down and landed outside his door.
"Good evening, Shinobu Kocho, Nanajūhachi Asuka. The moon is beautiful tonight."
Asuka turned his head and realized it was not his own crow, but one wearing a purple scarf, its voice calm and intelligent.
Before Asuka could respond, Shinobu Kocho smiled and greeted it first. "Good evening, Messenger."
The crow nodded and looked at Asuka. "A pleasure to meet you, Asuka. I am the Kasugai Crow of Ubuyashiki. You may call me Messenger."
Messenger? Master's crow?
"Though I would enjoy admiring the moon with you both, business comes first. Nanajūhachi Asuka, I relay the following order:"
"The number of victims aboard the Mugen Train has increased. Over forty people have gone missing, including members of the Demon Slayer Corps."
"Proceed to Saitama Prefecture in the west. Rendezvous with the Flame Hashira, Rengoku Kyojuro, at the scene. Locate the demon and eliminate it."
"That concludes the order."
Mugen Train...
Asuka looked at Shinobu Kocho and asked seriously, "Shinobu, what is a train?"
He was not joking. He genuinely did not know.
Since leaving the mountains, he had always traveled on foot during field missions. He rarely even rode in carriages, let alone... a train?
Seeing the confusion on the crow's face, Shinobu Kocho covered her mouth and laughed softly. "Please don't be surprised, Messenger. Asuka has been training in the mountains all this time. There are many things he hasn't encountered."
"I see. Forgive my presumption." The Messenger adjusted the small feathers on its head with its wing and continued, "In any case, please make your way to Saitama as soon as possible and join the Flame Hashira. Investigate the cause of this incident and proceed with caution."
"Messenger, may we add a few more people to the team?"
"Oh? Does the Insect Hashira wish to participate as well? Three Hashira might be a bit..."
"Not me. Tanjiro and the others." Shinobu Kocho explained, "These three children have recovered. They're growing quickly. Taking on more difficult missions may help them improve further."
"And Tanjiro once mentioned that his family has passed down a Kagura dance similar to Sun Breathing. I believe Rengoku may be able to offer him some guidance."
At the mention of Sun Breathing, the crow's eyes narrowed slightly. "...I understand."
It nodded and spoke on behalf of Ubuyashiki. "Asuka, as an A-rank swordsman and a prospective Hashira, you are already qualified to lead Demon Slayer Corps members on missions. Tanjiro and the other two will be placed under your command."
"Understood. Do we depart immediately?"
"The sooner the better. The Mugen Train runs every day. No one knows if more people will disappear."
"In that case, I'll go now—"
Shinobu Kocho stopped Asuka, who was about to head out to find Tanjiro and the others. "Wait a moment, Asuka."
She turned to the Messenger. "Let them depart tomorrow. Asuka doesn't even know the way to Saitama. It's best to prepare first."
"Very well. You are correct. Then I shall take my leave. Good night, ladies and gentlemen."
The Messenger was only there to relay orders and would not force immediate execution. After a polite farewell, it flapped its wings and departed.
The Butterfly Mansion grew quiet once more.
"Asuka, this is your first time leading a team. You must remember..."
The night wind whispered. All farewells come eventually.
The days at the Butterfly Mansion had been among the rare few peaceful times in Asuka's life.
Spending time like this, chatting idly with others without purpose—it was not bad at all.
Asuka listened carefully as Shinobu Kocho explained the route to Saitama, the customs along the way, and the details of how to properly arrange his team as a captain.
Most importantly, she reminded him that as a leader, he could not focus solely on fighting.
He had to protect his subordinates. He had to protect the civilians around him. That was the duty of a leader.
Watching her earnest expression, Asuka felt a faint sense of melancholy.
If there were no demons in this world—no battles, no evil beings who abused power—how wonderful it would be if everyone could live such peaceful lives.
He did not sleep that night.
Early the next morning, after Tanjiro and the others completed their final assessment, Asuka informed them of the mission.
"For this mission, I am the captain. If danger arises, you do not need to fight. Wait for me to handle it," Asuka ordered calmly. "I will protect you. Do not worry."
"Hah?! I don't need anyone protecting me!" Inosuke clearly bristled.
He knew Asuka was strong, but he had never witnessed it personally. As far as he was concerned, this so-called prospective Hashira was nothing special.
Maybe just a little stronger than Kamaboko Gompachiro—but compared to the mighty Lord Inosuke at full power, probably still lacking!
Asuka nodded. "There will be many civilians on the train. Inosuke, you must take responsibility as well. Protect the weak."
"Tch, of course I will!"
"Asuka, do you think the demon on the train... could be one of the Twelve Kizuki?" Zenitsu asked anxiously. "Forty people missing—it doesn't seem like the work of an ordinary demon..."
"I don't know. But I will kill it."
Asuka tightened his grip on the Asauchi at his waist and looked at the brightening sky. "Let's go. We must reach Saitama as soon as possible."
"Yes!" Tanjiro responded firmly, fastening his checkered haori.
Before departing, they bid farewell to everyone at the Butterfly Mansion.
Tanjiro turned to Kanao and encouraged her energetically, "Do your best, Kanao! The heart is what drives us! The heart can become infinitely strong!"
"Always follow your heart—and take good care of yourself!"
"...You too. Have a safe journey."
Huh? Kanao actually spoke to someone?
The members of the Butterfly Mansion stared in disbelief, unable to understand what had just happened.
"I'm telling you, stop eating random things. You'll ruin your stomach."
"Haha! I'm the king of the mountains! How could I get a stomachache?"
"Enough nonsense. Here."
On the other side, a Butterfly Mansion girl with twin tails and a blue butterfly hairpin shoved a lunchbox into Inosuke's arms, looking exasperated.
"These are proper rice balls. Eat them when you're hungry. Don't just pick fruit at random!"
She was Aoi Kanzaki, one of the Butterfly Mansion members responsible for Tanjiro and the others' recovery training.
Though she appeared cold, she was actually very warm-hearted and had always cared deeply about their health.
"Whoa! I'm eating it now!"
"No! You idiot!"
Watching their noisy exchange, Shinobu Kocho laughed.
This smile was genuine. Asuka could feel the joy radiating from her.
"We're going, Shinobu."
"Mm. Be careful on the road."
Shinobu Kocho handed Asuka several test tubes filled with brown liquid.
"These contain some herbal sleep medicine. If the nightmares worsen, drink one before bed next time. It will ease them temporarily."
"Thank you. I'll be careful."
"Asuka..." Shinobu withdrew her hand, concern flickering in her eyes. "Be careful. Remember our promise."
Asuka nodded solemnly and extended his little finger toward her.
Though no words were spoken, they both understood.
The four of them dashed down the mountain in a flurry, heading west.
In the distance, darker clouds were gathering.