With one year left until the original story, Nezuko and I once again bought gifts and arrived at Tanjiro's house. Kie was still caring for the baby.
"Nezuko, would you like to examine your mother?"
"Yes, I'll try."
At my words, Nezuko took a stethoscope and began examining Kie, touching various parts of her body.
"Hmm... Right now, Mother, due to frequent childbirths, your pelvic floor muscles have weakened, and your uterus has descended significantly. If this continues, your uterus will press on your bladder, worsening your incontinence, and if things go wrong, a uterine prolapse could occur. Additionally, due to malnutrition, I believe you are suffering from fatigue and anemia."
Kie seemed a little surprised by Nezuko's accurate examination.
"Oh my! How do you know that without me saying anything?"
Nezuko, looking embarrassed, said, "Heheh, I learned diligently from my teacher."
I patted Nezuko's head in praise.
"Well done, Nezuko."
I looked at Tanjuro and said, "As you heard from Nezuko, if she has any more children, your wife's health could be ruined. And your wife needs to rest and eat well."
Tanjuro seemed to take it seriously. "I see. Understood."
Then the children also hugged Kie and said, "I'll help you diligently, Mom."
"Me too!"
Before leaving, I called Tanjuro and Kie outside, handed them several boxes of condoms, and explained how to use them.
"During intercourse, use them like this. That will prevent pregnancy."
I also handed Kie some nutritional supplements.
"These are supplements. Take one after each meal. If you get pregnant again now, it could be very dangerous, so you need to be careful."
"Understood. Thank you."
I also attached a Shadow Soldier there. Since the timeline of the original story was approaching, it was to prepare for an attack.
Now, it was time to get in contact with the Demon Slayer Corps. So, after saying goodbye at Tanjiro's house, Nezuko and I got in the car and headed for the Demon Slayer Corps headquarters, where 'Ubuyashiki Kagaya' resided.
"Teacher, where are we going?"
When I didn't go to the clinic but elsewhere, Nezuko asked. So I explained about demons to Nezuko.
"Are you saying such monsters exist in the world?"
"Yes. So we're going to the Demon Slayer Corps, who hunt those monsters. I have something to learn from them."
"I-I see."
Nezuko seemed slightly unbelieving as we traveled. It was an unbelievable story, even for me. Since Nezuko had no prior knowledge, her situation was a bit different from her father, Tanjuro.
Anyway, after a long drive, we arrived at the Ubuyashiki estate, the headquarters of the Demon Slayer Corps. However, they did not seem particularly welcoming.
"Who goes there!!??"
I got out of the car holding a pre-made Nichirin Blade. Nezuko tried to get out of the car as well, but I told her to stay inside. If things went wrong, they might attack.
"I've come to meet the Ubuyashiki leader."
Since it was still daytime, they knew I wasn't a demon. One of them went inside to report, while the remaining members pointed their swords at me and stood on guard. I leaned against the car and simply waited.
After some time, a Demon Slayer came out and said to me, "The Master says he will see you."
As they opened the gate, I drove the car inside. The Ubuyashiki estate was large enough for a car to enter. I parked the car in a suitable spot, got out with Nezuko, and followed the Demon Slayer's guidance into the estate.
"Uwaah~ The house is huge."
Nezuko, following behind me, marveled at the size of the Ubuyashiki estate.
"Why? Do you want to live in a house like this?"
"No, a house like this seems hard to clean."
"People who live in houses like this don't clean it themselves. They hire people."
"Is that so?"
While Nezuko and I were talking about this and that, we arrived at a large living room. There, 'Ubuyashiki Kagaya' was seated, drinking tea. Two cushions were laid out in front of him, seemingly prepared in advance. So I sat down first, and Nezuko, watching my cue, sat beside me.
Then Kagaya spoke first.
"What business does a doctor from the West have with me? And carrying a Nichirin Blade at that."
It seemed he had done a quick background check on me. And his voice was quite pleasant.
"Muzan is giving you a headache, isn't he?"
At my words, Kagaya seemed very surprised.
"I'm increasingly curious about your identity. Not only do you know Muzan's true nature, but there have been no reports of such a Nichirin Blade being made."
He recognized it as a Nichirin Blade even though I hadn't drawn the sword.
"I made this sword myself."
"That's impossible. There is no place other than the swordsmith village that can make Nichirin Blades."
"That's just your thinking. Anyway, let's stop the idle talk and get straight to the point. I'll capture Muzan for you. In return, I would like you to teach me all the breathing techniques."
At my words, he looked dumbfounded.
"Do you think that's possible? Muzan is not a monster that can be caught as easily as you say."
"It is possible. If you don't believe me, let's test it."
Kagaya then called for someone. Before long, a Demon Slayer entered. Even at a glance, he was a well-trained man.
"Then, let us see your skill."
"One person won't be enough."
"That will be sufficient."
The Demon Slayer and I faced each other in the courtyard. Nezuko was fidgeting restlessly as she watched. She didn't say anything, but she seemed worried.
"Then, please begin."
At Kagaya's signal, the Demon Slayer, seeing that I didn't draw my sword, glared at me and asked, "Why aren't you drawing your sword?"
"I don't need a sword to fight you."
"Arrogant. You'll regret it."
He ran at me and swung down his sword. I lightly dodged the first strike, then immediately struck the back of his neck with a knife-hand chop fast enough to knock him out.
Thwack!
Thud!
He crumpled forward, still holding his sword, seemingly unaware of why he had lost consciousness.
"See? I told you one person wouldn't be enough."
"I-I see. Understood. It's getting late today, so please rest. We can talk again tomorrow."
The sun was already setting, so I nodded. This time, a girl with white hair, like a doll, guided Nezuko and me to our lodgings. She was probably one of Kagaya's twins, 'Kanata' or 'Kuina'.
"Guest, would you like to eat first, or bathe first?"
At those words, I looked at Nezuko.
"I... I'd like to eat first."
"Understood. Then, I will prepare the meal."
We waited in the room, and a meal was brought. It was prepared with care, and it was delicious. We ate, bathed, and then lay down in the room to sleep. Nezuko laid out her futon next to mine in the same room. Since this was our first time here and we hadn't established trust with them, there was no choice.
"I didn't know you were that strong, Teacher."
Nezuko turned toward me and said.
"There is no one on Earth stronger than me."
"Come on, surely not. Teacher, you're good at joking too."
Nezuko didn't believe me.
"You need to get strong too. The world is more cruel than you think. To practice medicine, you need to be able to protect yourself."
"I see. Understood."
It wasn't wrong. Even setting aside the demon issue, it was still an era where common sense didn't always prevail.
The next day, as we waited, talking among ourselves, I saw the Hashira coming into the courtyard one by one.
"Why did you suddenly summon us? Oh my! There's an incredibly handsome man here."
'Shinobu Kocho' looked at me in surprise, staring intently.
"Ahem, stop staring."
"Oh, I apologize. It's just so amazing that such a handsome person actually exists. Not a single blemish on his skin. Are you really human? Since you're out during the day, you're certainly not a demon, but..."
Then Nezuko moved close to me, tightly hugging my arm, and glared at Shinobu warily. Shinobu saw this and smiled.
"Heheh, come to think of it, there was a cute little girl beside you too. Is she your sister? I'd like to ask, but she doesn't resemble you."
"She's my assistant and student."
"Assistant, you say…"
"I'm a doctor."
"Ah~ I see. Nice to meet you. I'm Kocho Shinobu. I'm also very interested in medicine."
Shinobu smiled and greeted me.
"I'm Jin. Nice to meet you."
Then 'Sanemi Shinazugawa' grumbled, "How long do they intend to keep us waiting? I came running without sleep because I thought it was urgent."
I glanced around at them. Apart from the Stone Hashira 'Gyomei Himejima' and the Serpent Hashira 'Obanai Iguro', it seemed all the others had come. Just then, the twin sisters Kanata and Kuina appeared and called out to them.
"The Master has arrived."
At those words, all the Hashira knelt on one knee and bowed their heads. Then 'Kagaya' slowly walked out.
"Thank you for coming, except for those on distant missions. I'm glad to see you all looking healthy. Hmm... The warm sunlight feels good—the weather is nice today. It's just after lunchtime; I hope you've all eaten."
Then Sanemi raised his head and said, "I am merely glad to see that you, Master, are also well. I earnestly wish for your continued happiness."
"Thank you, Sanemi."
"Master, I would like to know why you called us here in such a hurry, when it's not even a Hashira meeting. If you don't mind."
"From now on, I would like you all to spar with the man here. All of you."
Kagaya pointed at me as he spoke.
"Excuse me??? What do you mean…"
Kagaya's shocking statement left Sanemi and the other Hashira looking dumbfounded.
"I'm sorry, everyone, for issuing such a strange order. But this matter is very important, so I ask that you take it seriously."
Then he looked at me and said, "Then, I leave it to you, Teacher Jin."
"Very well."
I rose from my seat and stood before them. I then took out a small dagger from my pocket. Seeing this, Sanemi looked incredulous.
"What is your scheme! Are you trying to mock us right now!"
"I'm different from fools who go all out even when chasing a rabbit. Ah, not a rabbit. An ant? But unfortunately, I don't have a sword smaller than this."
At my words, Sanemi's temple veins bulged, and he turned to me with a fierce expression.
"Wha-What did you call us? Ants???"
After saying that, he turned to the other Hashira and said, "Don't you interfere. I'll kill him!"
Then he drew his sword, charged at me like a madman, and shouted, "I'll slash that pretty face of yours to ribbons!!!"