If he could overcome this weakness, then in the future, Muichiro wouldn't have an indirect kiss with a man... But breathing is indeed a weakness. Humans must breathe, even Ninja get flustered if they're trapped in a water prison for ten minutes without breathing.
Later, Doma's Blood Demon Art was practically the bane of Breathing Techniques. One of his Blood Demon Art techniques was to scatter tiny ice crystals into the air, and when humans breathe, they inhale these ice crystals along with the moisture in the air, leading to poisoning.
This technique was practically the nemesis of Breathing Techniques. If you couldn't defeat him immediately, you would only grow weaker with each blow.
This highlights the importance of intelligence. If you knew the opponent's information, you wouldn't lose the fight, at least; a Wind Release could simply blow away his ice crystals.
Or a Fire Release... but it's not that easy. Even Lower Ranks have the strength of Jonin, and with their special immortal bodies, the Upper Ranks' strength cannot be underestimated. This has always been Uchiha Nagi's view: survival is paramount.
Underestimating others will only lead to being like Erzhuzi, who, despite having an Eternal Mangekyo, was stabbed to death by Madara.
"By the way, there's a mission. The Master asked me if you wanted to go." After training, Muichiro stroked his chin, suddenly remembering something.
"Hm? What mission?" Uchiha Nagi asked.
He saw his relationship with Kagaya Ubuyashiki more as a partnership than as a vassal or subordinate, and Kagaya Ubuyashiki didn't mind this at all. After all, being able to exchange Ninjutsu with Uchiha Nagi had already been a huge help to the Demon Slayer Corps.
"It's like this: information about a demon has come from a certain place, and all the swordsmen sent there have gone missing. Therefore, the Master suspects the presence of a Twelve Kizuki there."
Muichiro said, "A Twelve Kizuki. One Pillar might not be enough. Since you just joined, the Master would like to ask you to go together. Two Pillars going. Of course, the Master said he wouldn't force you. If you're willing, you can go to the Master and ask for the specific details."
Uchiha Nagi thought for a moment, then nodded, "Alright, I'll go over there later."
With a nichirin blade, Mangekyo, and Amaterasu, Susanoo, and Sword of Totsuka, if he still died that easily, it would be a plot-kill like Shisui's.
In the afternoon, Uchiha Nagi arrived at Kagaya Ubuyashiki's house—
Frankly, Kagaya Ubuyashiki was a broad-minded leader. For those who had seen demons and were timid, he would assign them to logistics. For older members, or those who were weary, injured, or disabled, he would allow them to retire. Some Pillars, after retiring, would become trainers for the next generation of Demon Slayer Corps, like Sakonji Urokodaki. Others would manage logistics like the Wisteria House, or some, like the Flame Pillar's father, would do nothing at all.
In short, working for him had a beginning and an end; you could retire or resign at any time.
There was no worry about being discarded after being useful, or being eliminated once your purpose was served, unlike a certain Third Hokage who, after several Shinobi World Wars, directly annihilated the Uchiha clan... Working with a boss of such magnanimity was particularly comfortable.
"Mr. Kagaya Ubuyashiki, Mr. Muichiro said you were looking for me?" Uchiha Nagi respectfully asked.
Although he was respectful to the other party, their relationship was one of cooperation, so Uchiha Nagi did not kneel on one knee, and the other party did not mind this.
"Please sit, Mr. Uchiha." Kagaya Ubuyashiki smiled, "I apologize, my eyes cannot see, so I'll have to trouble you to pour the tea yourself."
"It's fine." Uchiha Nagi didn't mind these things too much, pouring a cup for himself and a cup for the other person.
"To be honest, I invited you here today because I want you to go with the Flame Pillar. There's information about a demon appearing on a train, and a squad of swordsmen went to investigate, but they all disappeared. Alas..."
Kagaya Ubuyashiki sighed and began to explain the situation. A small squad went to investigate a missing persons incident on a train, but they all disappeared.
It's important to note that, although this squad included newly joined members like Tanjiro, who was a Mizunoto, it was led by two Kinoe-ranked members, which is equivalent to two Jonin leading a team, as Kinoe is just below a Pillar.
"So I suspect there's a Twelve Kizuki there. I've already sent the Flame Pillar, but after he left, I had a bad premonition. The Ubuyashiki family's premonitions are always accurate, so I wanted to ask for your help to go there."
"Alright, I'll go then. It just so happens I also want to learn Flame Breathing from him." Uchiha Nagi nodded.
"Thank you for your trouble. Your Kasugai Crow has also arrived. I will have someone take you there shortly. Oh, the train's name is Infinity."
Mugen Train—
"Ah, things haven't been peaceful lately. It's all because of that 'Ripper' along the railway line. The number of passengers has decreased significantly."
"Yeah, and these useless police haven't caught the culprit after all this time. We small vendors are the ones who suffer, still having to pay rent, sigh..."
"Indeed, I heard the number of missing passengers has already reached over forty..."
Next to the bustling train station, there were many people coming and going, transporting goods, but there were very few travelers. Some small vendors selling peanuts and melon seeds looked distressed as they read the newspaper.
They hoped to see news of the culprit being caught in the newspaper, and at the same time, with troubled expressions, they called out, hoping passing passengers would buy something. A crow stood on Uchiha Nagi's shoulder. Luckily, this one wasn't a chatterbox like Tanjiro's, or he'd be annoyed to death, nor was it a sparrow like Zenitsu's, because he didn't understand bird language.
The crow led him to the train station. This world was roughly in the steam age, with cars, electric lights, and electricity, but no television. The way of spreading news was still through newspapers.
Uchiha Nagi wondered if, after Muzan was eliminated, he could travel to other countries to see what kind of extraordinary powers they possessed.
"Hello, are you the Pillar, Mr. Uchiha?" A young man who had been waiting at the train station for a long time became excited when he saw Uchiha Nagi, recognizing the crow on his shoulder as a partner unique to the Demon Slayer Corps.
Uchiha Nagi was a newly promoted Pillar, but his title hadn't been decided yet, because most Pillars before him inherited the same Breathing Technique, but he was a bit special... "My name is Murata, and I'm the Mizunoto member assigned to meet you."
"Hm, thank you for your trouble." Uchiha Nagi politely nodded to him.
"Oh, oh, you're welcome. Let's get on the train first. The tickets have already been bought. According to the information from the crow, the Flame Pillar has already departed to investigate the Mugen Train. We'll take this train to catch up and meet him."
Murata scratched his head, not expecting a Pillar to be so easy to talk to.
Uchiha Nagi nodded, and then the two took their tickets and boarded the train...