After finishing the breakfast, they started traveling again. 

The journey back to the Butterfly Mansion was slow but steady. Feeling the pain decrease a little, Kenshi decided to walk rather than continue the awkward traveling he had experienced the previous night.

Although it was still painful he endured the discomfort. Reaching the mansion and reporting his findings took priority over his own comfort.

Kanao walked beside him, glancing worriedly at his rigid, tense posture as he limped along. She wished they could rest more, but understood his urgency to speak with Shinobu.

Akari took up the rear, her sharp eyes scanning their surroundings for any threats. The forest was calm, but she remained alert.

By late afternoon, the pink walls of the Butterfly Mansion finally emerged between the trees. Kanao's shoulders relaxed slightly at this ight.

Shinobu met them on the porch, graceful as always in her orchid-patterned kimono. Her eyes, however, were grave. 

"Welcome back,." She greeted them somberly. "I am relieved to see you both safe. Come inside and tell me what happened."

Before they moved, Shinobu turned back and looked at Akari. 

Akari noticed her gaze and introduced herself. "My name is Akari Hayashi, although I know Lady Kocho might not remember me. You treated me once when I had a severe injury during a mission."

"She helped us reach here." Kenshi added.

"Oh, in that case, thank you for helping my students. You can come inside with us." Shinobu said as she made her way inside the mansion.

They followed her in and were swiftly treated for their injuries.

"A fracture below the knee, and minor fractures in the toes. I never thought you would be injured this badly on your first mission." She said, looking at Kanao and Kenshi. They could both clearly sense the tension in the air as they started recounting what had happened in Sakurai Town.

Kanao gave a brief account of the demon and their confrontation.  

Shinobu's frown deepened as she listened. When Kanao fell silent, she turned to Kenshi expectantly. "And the rest? I sense there is more than you have not told me."

Taking a breath, Kenshi launched into an explanation - the demon's human slaves and followers, the mayor's betrayal, and the horrific underground facility he had discovered. With each new detail, Shinobu's fair skin grew paler.

"Experiments to create artificial demons...and you believe this 'Edward' the mayor mentioned is somehow behind it all?" she murmured once he had finished.

Kenshi nodded grimly. "I found clues pointing to that. He could be as big threat as Muzan himself. I mean, Muzan only kills humans but never uses them. With this, there will be many questions, like are there any traitors in the Demon Slayer Corps and such." 

Shinobu was silent for a long moment, staring into the distance. "This is extremely troubling matter." She said finally. "If demons have begun allying themselves with humans in this manner, it poses a grave danger to us all. The other Hashiras and Master must be informed immediately."

After treating his and Kanao's injuries, she rose up. "Rest now. I will go speak with the Master and call an emergency meeting. We must get to the bottom of this." With a swish of her orchid kimono, she swept from the room. 

Kanao watched her sister disappear down the hall, worry in her violet eyes. Kenshi sank back against the pillows, exhaustion seeping into his bones. Telling his report had drained what little energy he had left.

Soon after, Akari stepped quietly into the room. She had lingered outside respectfully during Kenshi's private discussion with Shinobu.

"That was a detailed report you gave Lady Kocho." She remarked, studying Kenshi curiously. "You investigated that underground base thoroughly after the battle, despite your injuries. Most Demon Slayers would have retreated immediately."

She tilted her head. "Why did you suspect this...Edward, was it? I'm very interested to know more details of your confrontation with the demon." 

Kenshi looked at her. 

"Before I tell you anything, tell me about yourself and the demon you're tracking. Since you've heard what I've told Shinobu, you're also a possible suspect." He said. As he finished his words, he sensed the angry glare of Akari.

"I will indeed tell you about that, but don't ever again mix me with those disgusting demons and the traitorous pigs who become slaves of demons," she said sharply.  

Kenshi nodded and showed a curious response.

"I was an orphan and chose to become a demon slayer after the demons killed the orphan owner and many of my friends.

"As for the demon I am searching for, a few days ago I got a mission from the crow telling me that in a town called Reji, old people started disappearing one after another. When I went to the town, I didn't encounter any demons so I changed my plans and started looking for clues. I found that in the nearby town called Sakurai, the same situation is happening. 

"However, rather than disappearing, they are dying. At first no one cared since death comes naturally at old age, but panic started when too many people started dying. That's why I came to Sakurai Town." She said all that in one breath. 

Kenshi looked a little dazed as he contemplated. 'Old people are dying? I never heard anything about that in the last two days I stayed there. Could it be in some other part of town? Sigh, I am too tired to think about all of this.'

He stopped and looked at Akari. She had proven herself an ally, so perhaps sharing some of his suspicions would be beneficial. And he could use another perspective.

"You asked about the confrontation, right?" 

He went on to give Akari a condensed account of the battle itself and how the mayor acted, explaining how this demon was different from any other they had encountered. She listened intently, her eyes narrowed.

"A foreign name...that is suspicious." She mused when he had finished. "Perhaps this Edward is not from Japan but from further abroad. To have developed such advanced ways of creating demons..." She shook her head. "We must find out more about him."

Kenshi nodded. "I agree. Hopefully the other Hashiras can start investigating this soon. We need to act fast, before the danger increases."

They sat in silence for a moment, contemplating the potential danger. This shadowy new enemy could change everything if they did not stop him quickly. 

After bidding Kenshi rest, Akari left to compose her own report. Kenshi lay back, questions spinning through his exhausted mind until he finally slipped into the sleep.

Elsewhere, Shinobu had finished briefing Kagaya Ubuyashiki on the situation. The Master's expression was deeply troubled.  

"This is alarming news," he said gravely. "If demons and humans are forging alliances, the Corps will need to exercise even greater caution during missions. And we must learn more about this Edward."

"Indeed." Shinobu agreed calmly, though inwardly she also understood his concerns. "I suggest sending Hashiras to investigate the town immediately. Any clues we can uncover may help us find out mor about this threat." 

Kagaya nodded. "Very well. I will summon the available Hashiras to plan our next move." 

Messenger crows were swiftly dispatched across the region to gather the Hashira. By the next evening, three Hashiras had arrived at the Corps headquarters. 

Shinobu brought them up to speed on the situation. The reactions ranged from shock to skepticism to anger. 

"Preposterous! Demons would never work with humans." Wind Hashira Sanemi Shinazugawa scoffed. "You expect us to believe they're performing freak experiments together? Hmph."

"I agree it seems far-fetched." Said Water Hashira Giyu Tomioka quietly. "We should investigate thoroughly before jumping to conclusions." 

Meanwhile, anger simmered in Mitsuri's green eyes. "How could any human ally themselves with those monsters after the suffering they've caused?!"

Once the initial outbursts of their's passed, Kagaya's messenger crow circled in the air, calling for attention. 

"Master Ubuyashiki has considered the matter carefully." The crow declared in its eerie, childlike voice. "He ordered that Wind and Water Hashiras should travel to Sakurai Town immediately to investigate the underground facility and any other clues. Additionally, all Demon Slayers must exercise extreme caution on missions regarding potential human involvement with demons until we understand this threat." 

With their instructions received, final preparations were swiftly made. By morning, Shinobu stood at the gates once more to see off the Hashiras.

"Tread carefully." She told Giyu and Sanemi grimly. "We do not know what dangers may lurk in that town."

Giyu didn't respond and Sanemi simply scoffed and started walking away. 

Shinobu watched the odd pair go, veiled anxiety in her eyes. She wondered why Master Ubuyashiki would send Sanemi, who would probably kill any human who had betrayed humanity. Perhaps it was because Giyu was going along to stop Sanemi if he does anything crazy.

She prayed their investigation would unveil useful information about the mysterious experiments and this new threat. If they did not act quickly, they might have to face a catastrophe...