The two did not stay on Mt. Sagiri for too long.
After leaving behind "Haruto Mark I" (which was ultimately what it was named), capable of beating Tanjirou and Genya black and blue, they bid farewell to Haruto.
Before they left, Haganezuka Hotaru pointed at Tanjirou's red hair and eyes and was surprised for quite a while, calling him a "Child of Bright Flame" who would bring good fortune to families working with fire.
"Perhaps when you get your own nichirin blade in the future, the blade might turn as red as flames."
The muscular man under the Fire Man mask mumbled, "Then… when you join the Demon Slayer Corps, how about I forge your blade? I've never seen a bright red blade before…"
'And you want him to make it for you…' Haruto glanced at him sideways.
'Could it be that this guy is no longer satisfied with just chasing me around?'
The strength of the mechanical doll was just right for Tanjirou and Genya—just right meaning it could beat them up badly but not fatally.
However, amidst the torment of bitter and pain, the two boys' swordsmanship grew rapidly.
Under Genya's guidance, the two vowed to dismantle the puppet into a pile of shattered parts during their training.
'Heh, young lads.'
Kotetsu said he had already started making the second generation of "Haruto Mark I" mechanical doll, intending to make greater adjustments to its flexibility.
By the time the boys could defeat this mechanical doll, the second one would probably appear at home.
At night, Haruto wrapped in his haori went on his routine patrol.
There are many mountains around Mt. Sagiri, and scattered on these mountains live hunters, woodcutters, and other people who rely on the mountains for their livelihood.
After crossing several mountains, Haruto felt a bit sleepy.
He yawned at the moon, then sharply noticed a figure walking on the mountain path opposite him.
'Is it a demon?'
No, it looked more like a daring night traveler.
When Haruto got closer, he found it was a slender young girl.
The girl wore a headscarf, dressed like a hunter, and carried a long-barreled hunting rifle on her back.
A young hunting dog ran in front of her, and upon smelling an unfamiliar scent approaching, the dog turned its head and looked at Haruto warily.
The girl immediately reached for her hunting rifle, turned around, and shouted in a low voice, "Who's there!"
Haruto had no intention of hiding his tracks. He walked forward, holding his nichirin blade, but didn't get too close, so as not to make the girl and the dog too nervous.
"Are you a mountain dweller from here?" Haruto asked softly, "But I've never seen you before."
The girl didn't answer immediately. Her gaze slid down to Haruto's nichirin blade at his waist, and her expression relaxed slightly: "I don't live nearby, so of course you haven't seen me."
"Then do you have a place to stay? I mean, it's not safe to wander around outside at night."
Haruto raised an eyebrow. He noticed the girl's subtle change in expression but didn't understand the reason for it.
Logically speaking, upon seeing someone approaching at night carrying a weapon, shouldn't she be more vigilant?
"I know," the girl replied. "Sir, are you… from the Demon Slayer Corps?"
She pointed to Haruto's black uniform lining and the nichirin blade at his waist: "I once saw a swordsman who also wore the same clothes and carried a similar blade."
"Since you know about the Demon Slayer Corps, you must also know about the existence of demons. You don't look like a Demon Slayer Swordsmen, so why are you walking around at night?"
The girl sniffed, picked up the hunting dog that had jumped onto her lap, and her eyes drifted: "I'm just, I'm just… chasing something."
The rustling sound of a bird flapping its wings broke the silence. Haruto looked up and found it was a Kasugai Crow.
And this Kasugai Crow… Haruto found it very familiar.
"Kanzaburo?"
It was Giyuu's Kasugai Crow.
Haruto reached out a finger and caught the descending Kanzaburo, feeling a bit confused.
"Has something happened to Giyuu?"
The girl looked at Kanzaburo and moved her lips: "…Sir, this crow might be looking for me."
…After the girl's explanation, Haruto finally understood why she knew Giyuu.
Several months ago, when something happened to the Kamado Family, Giyuu had written a letter to Haruto, stating that he was searching for demons near Mt. Kumotori.
After the New Year, he finally difficultly received news of a demon.
The girl in front of him, Yae, had survived an attack, and the demon that attacked her was actually her father.
Giyuu had spent a lot of effort tracking Yae, who had run into the snowy mountains, to kill that demon, and also saved Yae, who, disheartened, was about to pull the trigger of her hunting rifle to commit suicide.
Since then, Yae had left Okutama District, where she had always lived, and began to wander in the mountains and forests.
She brought her hunting dog, Jiro, and while tracking information about demons, she would organize and compile this information and send it to Giyuu via Kanzaburo.
Giyuu would confirm the authenticity of this information and then slay all the demons wandering in the mountains and forests.
Haruto remained silent for a long time after hearing the girl's answer.
"But… you're not a Demon Slayer Swordsmen, it's too dangerous to wander around in the mountains at night."
"When I wanted to commit suicide, Mr. Giyuu stopped me. Although he spoke incoherently and ambiguously, I understood what he meant…"
"In short, I've seen demons, and I've been hurt by demons!" The girl raised her voice: "I'm no different from the Demon Slayer Corps!"
Haruto looked at her, sighed softly, and then said, "Speak."
"What?"
"Aren't you supposed to tell Kanzaburo—this Kasugai Crow—some news?" Haruto gently stroked the feathers of the elderly Kanzaburo with his fingertips: "Instead of having it fly back to tell Giyuu, and Giyuu making time to come over, why not tell me directly?
My name is Takanashi Haruto, and I am the person in charge of this jurisdiction. I handle all incidents related to demons here."
Yae stared at him blankly, then pulled out a notebook from her backpack, opened it, and showed it to Haruto.
She had come here tracking some strange sounds and strange smells, unsure if it was a demon, but at least it wasn't human.
"Strange smell?" Haruto rubbed his chin: "Is it some kind of stench? Demons always carry a pungent stench because they eat too many people."
Yae thought carefully for a moment, then shook her head and nodded.
"I only smelled that strange scent for a moment; the main tracking was done by Jiro.
That scent wasn't a stench, but rather similar to some kind of insect's odor.
However, the stench you mentioned, I did smell it when I first entered this mountain, but it has disappeared now."
'Insect scent?'
Haruto furrowed his brow, feeling something was amiss.
In Mt. Sagiri, Tanjirou's nostrils flared, and he awoke from his sleep.
'What's that smell? It's a bit like a bedbug… and it's getting stronger.'