"Good morning, Mr. Haruki!"
"Good morning, Mr. Haruki!" × 3
Aoi was airing bedding in the yard, arms full of freshly washed cloths. Three small girls bounced around her—Sumi Nakahara, Kiyo Terauchi, and Naho Takada—their voices bright as morning bells. When they spotted Haruki emerging from his room, they abandoned their tasks immediately to greet him in unison.
"Morning," Haruki replied, his voice still quiet but steadier than it had been three weeks ago.
Three weeks. That's how long Haruki had been living at the Butterfly Mansion, though he rarely ventured beyond his room during daylight hours. The others had learned from Shinobu that she'd rescued him during a mission— a young man with a severe skin condition that caused rashes in sunlight. His body was weak, which explained his need for rest.
His thin frame and pale skin made the story believable. They'd taken it upon themselves to care for him in small ways, checking on him regularly and keeping him company.
Aoi had noticed his sweet tooth early on. She'd begun making treats specifically for him—simple mochi, sweet bean paste buns, honey cakes—and leaving them outside his door. Every night when she collected the dishes, she'd find them scraped clean, not a crumb remaining. For a chef, there was no higher compliment. It made her want to cook for him even more.
The three younger girls had also adopted Haruki as their special project. They reasoned that since he couldn't go outside and was in poor health, he must not have any friends to play with. So they'd appointed themselves as his companions, spending hours in his room teaching him cat's cradle and other games. His clumsy, uncertain movements with the string only reinforced their belief that he needed their help.
One night, they'd insisted on reading him a bedtime story. Haruki, naturally energetic at night, had tried to decline. But they persisted, settling with a picture book. Within minutes all three had fallen asleep on his floor. Haruki had carefully carried each to his bed, tucking them in and spending the rest of the night watching stars by the window. They got quite the scolding for that.
"Do you know where Shinobu is?" Haruki asked now, scanning the courtyard.
"Lady Shinobu is in her laboratory," Aoi answered, setting down her bamboo basket and moving closer. Her expression shifted to concern as she studied his face. "Mr. Haruki, are you feeling alright? You look... paler than before. Much paler."
"Yes!" × 3
The three little girls crowded around him, their wide eyes full of worry as they peered up at his face.
"I'm fine," Haruki said simply.
Aoi wasn't convinced. When they'd first met, his complexion had been pale but not alarming. Now it was nearly translucent. He must be getting worse, she thought. He must be pushing himself too hard, pretending to be fine when he wasn't.
Her expression shifted to one of sympathy.
"?"
Haruki touched his own face, puzzled by her reaction. Was there something wrong with it? Some visible change he couldn't see?
The truth was simpler than Aoi imagined. Today he'd promised to give Shinobu blood samples—the final collection, she'd assured him. Shinobu was usually out on missions at night, and Haruki needed to replenish his strength through sleep during the day, so mornings were their only opportunity to meet. As for his increasingly pale appearance, that was the direct result of having five large syringes of blood drawn over the past three weeks. Even with his regenerative abilities, recovering by sleep alone was proving too slow. Fortunately, Shinobu had noticed his condition and promised that today would be the last time.
"I'm going to find her," Haruki said, stepping forward.
Before he could take two steps, small hands grabbed the hem of his clothes. He looked down to find all three girls staring up at him with six worried eyes.
"What's wrong?"
"Mr. Haruki, aren't you going to say goodbye to us?" Sumi's voice trembled. "You're not... dying, are you?
They'd grown fond of him—not just because he was good looking, but because he played with them without a trace of impatience. He never told them to go away or complained that they were annoying. Sometimes he even read to them, his voice growing smoother with each story. They'd learned he could read, though he seemed surprised by the discovery himself.
"That... Nakahara..." Haruki began, trying to remember which girl was which.
"It's Sumi!" the first girl corrected immediately.
"It's Kiyo!" the second chimed in.
"It's Naho!" the third added.
The three were persistently trying to get Haruki to use their first names properly. He hesitated, the names right there on his tongue, but something stopped him. He wasn't used to addressing people so familiarly, so directly.
Under their expectant gazes, he finally managed, "Well... goodbye."
The girls deflated slightly with disappointment, but as Haruki walked away along the shadowed corridor toward Shinobu's laboratory, they quickly rallied. Kiyo made two small fists and pumped them determinedly.
"Mr. Haruki must just be embarrassed! We have to work harder—until Mr. Haruki can call out our names directly without hesitating!"
All three nodded with renewed fighting spirit.
Aoi watched their antics with a mixture of amusement and confusion. "Why did you specifically want him to say goodbye?" she asked.
They replied in unison: "It's good to say goodbye, because then we'll definitely meet again next time!"
"Eh..." Aoi had no response to that childish reasoning.
. . . . . . .
Haruki knocked lightly on the laboratory door. After hearing Shinobu's muffled "Come in," he opened the door and stepped inside.
The laboratory was organized chaos—shelves lined with bottles and vials, a workbench covered in notes and equipment, the faint smell of herbs and chemicals in the air. Shinobu knelt on a tatami mat near a low table, her shoulders slightly slumped. She yawned as Haruki entered.
He noticed the dark circles under her eyes immediately, settling across from her.
"Are you okay?" he asked, the question coming more naturally than it would have three weeks ago.
"Ara~ Is Haruki worried about me?" Shinobu's expression shifted instantly to her usual playful smile, though it didn't quite reach her tired eyes. She'd been on missions almost non-stop recently, hunting demons through multiple territories. Even for a Hashira, the pace was exhausting. On top of that, she'd been spending every spare moment studying Haruki's blood samples. His blood was extraordinarily unusual—the cells behaved in ways she'd never seen before, regenerating at impossible speeds. She'd been researching for weeks and still hadn't reached any definitive conclusions. But she'd drawn enough samples now. It was enough.
"Yes," Haruki said simply, meeting her eyes.
"Eh?" Shinobu's hand flew to her mouth in genuine surprise. In the three weeks since meeting Haruki, she'd gradually come to understand his personality—he was somewhat emotionally dense, almost painfully earnest, not particularly good at communication, and he definitely didn't say intimate or caring things unprompted. What had changed today?
"You need to rest properly," Haruki continued, his expression serious. "You're pushing yourself too hard."
He studied her carefully—this small person carrying enormous weight, smiling while forcing herself past limits. Though he'd only known her three weeks, he'd concluded she was a good person. Everyone in the Butterfly Mansion was good. He hoped they would remain safe.
"Yes, yes, I know." Shinobu smiled genuinely now. "I think Haruki's vocabulary is expanding nicely. Much longer sentences now."
It was true. The current Haruki, despite looking even paler than when he'd first arrived, was noticeably more expressive. He no longer stuttered through his words. When she'd first met him, he'd seemed to be simply going through the motions of living. Now there were flickers of genuine emotion crossing his face, subtle but real.
"You're all good people," Haruki said, and the corners of his mouth turned up slightly.
Shinobu's eyes widened slightly at the sight. That small smile transformed his face, making him look less like a demon and more like an ordinary young man.
The transformation had happened gradually over three weeks. During that time, Haruki had learned—through books, conversations, and careful observation—what demons were and what the Demon Slayer Corps represented. Most Corps members had been hurt by demons in some ways. That pain had driven them to join without hesitation, dedicated to ensuring no one else would suffer as they had.
They'd taken responsibility for killing every demon in the world, with Hashira like Shinobu as strongest combatants. Their ultimate mission was killing the progenitor of all demons, Muzan Kibutsuji.
Whenever Haruki thought that name, his entire body would heat up from within. Something deep in his cells seemed to pulse with warning, as if his very blood was cautioning him against speaking it aloud. He wasn't sure what it meant, but perhaps he would understand when he encountered this demon progenitor. If he ever did.
The point was this: Shinobu, as a Hashira, had brought a demon home. Once discovered, she would pay an enormous price. The other residents of Butterfly Mansion might also be implicated and punished. Yet despite knowing all this, she'd allowed Haruki to live here in peace, had protected him, had treated him with kindness instead of killing him on sight.
Haruki didn't want such a person to be hurt because of him. He couldn't allow it.
His decision solidified. He would leave within the next few days, before his presence could bring disaster to this place.
"You're all good people," he repeated, his voice firm with resolve. "I can't let you be implicated because of me. I'll leave in the next few days."
Shinobu's expression flickered—surprise, then something complicated and difficult to read. She'd half-expected this, honestly. She knew Haruki's character by now. He was stubborn in his own quiet way, immovable once he'd made a decision. Trying to convince him to stay would be pointless.
She sighed softly, straightening her posture and placing her hands formally on her thighs. Was letting Haruki leave the right choice? She genuinely didn't know. It could be dangerous—for him, for others. But she also knew she couldn't keep him here against his will, and keeping him here indefinitely would eventually lead to discovery.
So she chose to trust him. It was a step she'd never thought she'd take—trusting a demon. If she came to regret it in the future... well, that would be her future self's problem to deal with.
"I understand," she said finally. "Then, Haruki, have a safe journey."
"Yes."
Haruki extended his hand toward her across the table.
Shinobu stared at his outstretched hand, momentarily frozen. Then, almost reflexively, she reached out and grasped it, her small hand disappearing into his larger one. She hadn't expected him to want to shake hands. It was such a human gesture, so formal and final.
His hand felt rough against hers—calloused and worn in a way that seemed wrong for someone who looked so young. How did a young man get hands like this? What had he done before losing his memory?
Lost in thought, she held his hand longer than necessary.
Haruki shifted slightly, puzzled. "That... aren't you going to draw blood?"
"?"
"Draw blood?"
Realization hit Shinobu like cold water. He hadn't been offering a handshake. He'd been offering his hand for the blood draw. Her face flushed with embarrassment as she quickly pulled her hand back.
"Oh! Yes, of course. The blood draw. Right."
Then she drew two full syringes instead of one as revenge for making her embarrassed. Haruki accepted this without complaint.
Thanks to that double draw, Haruki ended up sleeping for two full days, his body desperately trying to recover. During that time, Sumi, Kiyo, and Naho visited his room regularly—sometimes together, sometimes taking shifts. They'd press their ears to the door, listening for breathing sounds. If Haruki hadn't continued showing faint signs of life, they would've been convinced he'd died.
. . . . . . . .
When Haruki finally woke and prepared to leave, it was late on the third night. He'd said quiet goodbyes to those awake, received tearful promises from the three girls, and accepted food from Aoi.
Now he walked through the darkened mansion, heading toward the exit. But as he passed through one of the outer corridors, he noticed a figure sitting under the eaves, silhouetted against the night sky.
It was a girl he hadn't seen before—young, wearing a pink kimono with a black side ponytail. She sat with perfect posture, utterly still.
Was she also from the Butterfly Mansion?
The girl was Kanao. When she sensed movement, she turned and noticed Haruki for the first time.
This was their first meeting. If she hadn't looked carefully with her exceptional vision, she might not have recognized him as a demon. He looked like a pale, thin young man.
Two pairs of calm eyes met. Neither spoke.
Should I say hello to him/her? Both of them thought simultaneously.
Haruki looked away first. He wasn't good at talking to strangers, and he'd already decided to leave. It would be better to go quietly rather than cause more trouble or confusion. He turned to walk away.
Behind him, a crisp metallic sound rang out—a coin being flipped into the air.
Haruki turned back, curious despite himself. He watched the coin spin and glitter in the moonlight.
"Pa."
Kanao caught it and pressed it to her hand. She checked the result.
Heads meant talking to him. Tails meant staying silent.
It was heads.
Kanao raised her head to look at Haruki, who was still standing there, watching her with obvious confusion about what she was doing.
"Hello," she said, her voice soft but clear in the night air. "I am Kanao Tsuyuri."