After conversing with Tanjiro and leaving behind the medicine, Hiru headed to Wisteria House in the town below the mountain. She informed the manager that she would be staying until next spring.
"Understood. I'll arrange accommodations for you right away."
Inko, who worked at the Wisteria House, replied respectfully. "Um... Mr. Mikazuki is also here. Would you like to speak with him?"
Hiru paused. "Why is he here?"
"It's said to be because of the family up on the mountain..."
"I see... Where is he?"
"Mr. Mikazuki has been in the medicine room. He said he won't leave until he's replenished enough medicine for our entire region."
"That does sound like something he'd do... I see. You two go back to work."
"Yes, sir. I'll take my leave then."
"Supplying medicine... I haven't specifically helped with that before, though I do leave any surplus behind when passing through..."
Hiru watched Kakushi jog away. "I'm a bit curious, actually."
Hiru sniffed the air, following the scent of Wisteria to its strongest point. Sure enough, he found Mikazuki in the courtyard, tending a large cauldron as he simmered something.
[His technique is so rough.]
That was Hiru's first thought.
But he quickly realized that meticulously refining such large-scale medicinal supplies would multiply both costs and time. Naturally, he walked over to assist Mikazuki.
"Hm?"
Mikazuki glanced at the processed herbs placed beside him, only then noticing his new helper. His expression froze in surprise. "Hiru? When did you learn to conceal your aura?"
"Ah, well... there's a rather timid little demon in Momoyama," Hiru chuckled, "so I deliberately practiced controlling it. Turns out it works surprisingly well." He smiled. "How about that? Quite the shock, huh?"
"Haha, shouldn't I be the one surprised?" Mikazuki chuckled. "Yoriichi would be delighted. You should write him about this."
"No, please keep it a secret... If my brother finds out, he'll push me to train again. He only just gave up on that."
"Haha, so even Hiru has fears—wait, that extract over there should be added last."
"Won't that weaken the potency?"
"But when batch-producing, adding it early causes too much evaporation. It's better to add it later, letting it seep in as the medicine cools."
"I see... I've never tried large-scale medicine brewing before, so I'm not familiar with that."
Mikazuki stoked the fire beneath the cauldron. "I know about the medicines you make. Sometimes those with side effects can affect the team members."
"I've instructed them on usage. Who'd be dumb enough to get poisoned?"
"You think everyone's as sharp as you?"
"No, I'm using all six brains at once."
"...Is this some new joke? Sorry, I'm just an old fogey."
Hiru: ...(－"－)
[When I don't want to be exposed, I'm sharp as a tack. But when I want to reveal myself, no one believes me. What exactly is the Demon Slayer Corps trying to accomplish?]
"Alright, now we just watch the heat," Mikazuki said, smiling at Hiru's oddly complex expression. "What? Upset because you didn't get your new joke?"
After a brief silence, Hiru silently added more firewood to the pot.
"...I don't feel like talking right now."
"Don't be so stingy. Come on, I'll treat you to dessert."
"You're up to no good."
"Of course not. I'm a totally reliable adult."
"Alright, that's all done now," Hiru stood up and clapped his hands. "I'm off to paint."
"Hiding away in your room again? That's not good, is it?"
Hiru merely dumped the pile of various medicines he was holding onto the table before speeding off.
"Honestly, even when she's angry, she's still so adorable."
Mikazuki looked down at the messy pile of various medicines on the table. The smile on his stern face widened slightly as he picked up the special gloves and put them on.
"Alright, now let me see what new medicines we have... Hmm? This one smells really strong..."
Mikazuki didn't linger long. Before he could fully analyze the substances, he took the medicines to ask Hiru about the effects of those new ones.
After receiving Hiru's explanation, he eagerly grabbed his medicine box, intending to head to Mount Fujikasane to conduct demon experiments.
Upon hearing this news, Hiru's expression was like this: (⊙_⊙)
"Are you a demon?" Hiru sat before his easel, looking up at Mikazuki. "Do you even hear yourself?"
"Ah, but isn't there a faster, safer way to find demons? You're the one with the skills, so you should do the work! Anyway, you only took half a year to fill your quota this time, right?"
"Huh? Are you serious?"
Honestly, if he hadn't been holding a paintbrush, Hiru would've genuinely wanted to punch Mikazuki.
"Can you act like a human being?"
"Haha, then next time, don't give me drugs with such interesting effects." Mikazuki slapped Hiru on the shoulder. "Now I'm completely hooked! I just can't calm down!"
"What's so fun about a drug that dissolves you on contact?" Hiru leaned back slightly. "Getting a kick out of that bloody scene... Are you a pervert?"
"...What gives you the right to say that when you're the one who developed that drug?"
"It's a tactic against enemies. Of course, the more cruel, the better. After all, enemies don't deserve mercy..." Hiru's gaze shifted back to the sketchpad. "I'm actually a pacifist who opposes violence."
Mikazuki recalled Hiru's superhuman strength capable of physically punching away demons, his expression instantly becoming one of profound exasperation.
"Seriously, do you even believe that yourself?"
"I do. I genuinely love peace." Hiru lowered his head, blending colors on the palette. "Joining the Demon Slayer Corps is the best proof of that."
"...Well, whatever. Just so you know, I'm taking the demon at Mount Fujikasane. Make sure to catch plenty of them when you get there." Mikazuki patted Hiru's shoulder with a smile. "Good luck—"
"Tsk... Fine, use it," Hiru glanced at Mikazuki's wooden prosthetic hand and sighed, his gaze pitying.
"Given your physical condition, I can't expect you to be a demon slayer independently anyway. I'll be magnanimous and tolerate you a little."
Mikazuki: ...