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1.
In the region around Yoshinagawa roams a female ghost, her whereabouts elusive, with a ghastly penchant for feasting on the hearts and livers of handsome men. Oyakata-sama has dispatched men to investigate time and again, but each mission met with grim outcomes: some Demon Slayers never returned, while those who did fell into violent emotional swings, consumed by anxious obsessions. Within days, they all wasted away in profound melancholy, their lives cut short.
In the end, the only recourse was to send a Hashira. Yet the ghost cared nothing for women, making Love Hashira and Insect Hashira unnecessary for the task. Wind Hashira is irritable and Flame Hashira is passionate—both seem easily stirred emotionally. Stone Hashira, perpetually tearful, and Snake Hashira, who refused to unwrap the bandages masking his face, failed to meet the ghost’s standards as a lover of fine looks; and Mist Hashira, still too young, left uncertain whether the ghost harbored a predilection for boys.
After weighing all options, Water Hashira emerged as the most fitting choice.
Oyakata-sama laid out the reasons to Giyuu in his usual formal manner, added a parting reminder: “Even the few who returned before perished from the aftereffects. Giyu, do not forget to report to the Butterfly Mansion for an examination first upon your return.”
Giyuu, as usual, replied in a deep voice, "Understood," then vanished into the night in a flash.
2.
Giyuu arrived at Yoshinagawa, but before he could even catch a trace of the ghost, a group of madams from the pleasure houses swarmed around him. They grabbed at him with eager hands, and the cloying stench of thick face powder clogged his nostrils, nearly smothering all his senses.
No wonder they swarmed: that vividly patterned haori, the crisp uniform, a face handsome enough to turn heads, and that wooden, tongue-tied air—anyone would peg him as a pretty, wealthy guy who is easy to deceive.
After years of slaying demons, dancing on the edge of a blade had become second nature, yet he’d never encountered a scene like this.
“What a handsome young man,” cooed one. “Come to our veranda—surely you’ll find a lady to match you.”
“Get your grubby paws off him, you old bat! We spotted him first!”
Giyuu felt confused. Why were they yanking him this way and that? He hadn’t the faintest clue what they wanted. As a man, his upbringing had never included a lesson on “guarding one’s chastity,” yet the situation stirred an unaccountable sense of panic in him.
In a daze, he was shoved into one of the pleasure houses. Staring at the carved screen before him, his soul echoed with three questions: *Who am I? Where am I? What am I doing here?*
From behind the screen glided a courtesan, her face powdered white, lips painted crimson. Her layered kimono skirts trailed like a waterfall across the floor, her full, scented shoulders bared to the air; one flutter of her lashes was enough to make a man’s blood race.
Surely, beauty like this was what upheld the prestige of such an establishment.
She lifted Giyuu’s chin with her folding fan, her voice coquettish: “Why won’t you speak, sir?”
In an instant, a flash of aquamarine blade light sliced through the air, severing the hand that held the fan. Yet she seemed not to care, as if such things were commonplace. She just smiled, soft and slow, while a new hand sprouted from the stump, smooth as if it had never been lost.
Giyuu’s grip on his Nichirin Blade tightened.
This was a demon—and one who’d feasted on many. She must be his target.
“How ungentlemanly,” she chided. “A little tenderness is how you win a lady’s favor.” Her movements were swift; in the blink of an eye, she was behind him. Her new hand stroked his cheek, and she breathed into his ear, “Won’t you talk to me? I have my sorrows too.”
Giyuu struck backward, driving his blade into her.
When the courtesan realized he truly meant to kill her, she threw herself into his arms. Giyuu grabbed her by the hair and lifted her, only to find her shape shifting into Shinobu Kocho’s.
Shinobu’s slender frame looked tiny in the courtesan’s garments, the fabric slipping to reveal a wanton expanse of skin.
“Who knew you’d prefer such a woman?” she purred, her hands coiling around his neck as she leaned in for a kiss. But before her lips could brush his cheek, her form snapped back to normal.
Her head rolled to the floor, its eyes fixing on the man with a look of loathing.
“To kill even the woman you love—are you even human? You’re the demon!”
Giyuu finally spoke his first words tonight: “You are not the woman I love. And I am no demon.”
The demon tried to spew more curses, but Giyuu paid her no mind and turned to leave.
Watching her wear Shinobu’s face, make that expression, speak those words—it sent a chill down his spine more unsettling than any ghost story Shinobu had ever told him.
A cool night breeze dispersed some of the cloying perfume clinging to his clothes. Giyuu let out a long breath.
Lucky he’d acted quickly. Otherwise, he might have vomited right there in the room.
3.
The kasugai crow flew ahead with tonight’s battle report, winging its way back to the Ubuyashiki estate. Giyuu, following Oyakata-sama’s instructions, first made his way to the Butterfly Mansion for an examination.
Shinobu had already heard about his mission from Oyakata-sama, but she hadn’t expected him to finish so swiftly.
After all, this demon had killed quite a few of their comrades—Shinobu had figured it’d be a tough opponent. Yet there wasn’t so much as a scratch on Giyuu.
“Good evening, Tomioka-san,” Shinobu greeted, holding an oil lamp and smiling softly. “How are you feeling? Anywhere not quite right?”
“I’m unharmed,” Giyuu replied. “I feel fine.”
“Come on in and sit. I need to draw a little blood for tests—it might take a bit.” Shinobu pulled out a chair, gesturing for him to sit, then selected a relatively fine needle.
Giyuu stared at Shinobu’s face and frowned slightly.
“Is that look of yours meant to be disdain for me, Tomioka-san?” Shinobu asked.
“It’s not disdain. The demon I met tonight took your form.”
“That sounds like quite the tale. And then what happened?”
“She tried to kiss me. I cut off her head.”
Shinobu blinked, her smile staying gentle as she quietly rummaged in the medical kit and pulled out the thickest needle there. Without a word, she jabbed it sharply into the vein on his arm.
Giyuu frowned again. “When you draw blood, it never used to hurt.”
Shinobu’s expression didn’t waver. “You’re misremembering. It’s always stung like this.”
She flicked the needle a few times, injected the blood into a vial, then used a cotton swab to spread some onto a slide, which she placed under the microscope.
“Mr. Tomioka, I can say for sure—you’ve been hit with a Blood Demon Art,” she said, looking up from the lens. “This one’s tricky. I might not have an antidote ready quickly, so you’d best stay at the Butterfly Mansion for now. That way I can keep an eye on you. Are you really not feeling anything off?”
Giyuu looked surprised. When had that happened? When the demon touched him? Or when she breathed in his ear? He’d had no idea.
Pressing a cotton ball to the puncture site, he nodded, then shook his head. “The spot where you stuck me hurts more than usual. Is that from the Blood Demon Art?”
“Oh my,” Shinobu said, her tone innocent, “who can say?”
4.
The next day, two entries appeared in Giyu’s medical record:
Patient has no visible external injuries. Blood tests show positive for residual Blood Demon Art; it is recommended that he remain at the Butterfly Mansion for observation.
Addendum: The patient appears to have sustained severe brain trauma. He should maintain a balanced diet and reduce his intake of salmon daikon.
5.
During the first two days at the Butterfly Mansion, Giyuu ate heartily and looked perfectly healthy. Though his blood tests remained positive, there was no visible sign of anything wrong with him at all.
He hadn’t had his beloved salmon daikon for three days. After dinner on the third day, he’d been in such a hurry to pack his things and leave that he suddenly collapsed in the courtyard. The sky was pitch-black, and Koya Kiyoshi, passing by, tripped over him before she even noticed. Glancing back to see the Water Hashira lying on the ground, she nearly jumped out of her skin.
But Shinobu and Kanao were both away on a mission and had been gone all day. Kanzaki Aoi and the other girls hurriedly carried him inside and sent a messenger crow to notify Shinobu. By the time she rushed back, Giyuu’s face was deathly pale, his lips were bluish, and his entire body was drenched in sweat.
Shinobu pressed her hand to his forehead and was startled by how cold he was.
These symptoms were identical to those of the previous affected Corps members.
No—that wasn’t quite right. The others had first experienced extreme mood swings, then recurring nightmares and convulsions, progressing to shock, with body temperatures consistently lower than normal. The anti–Blood Demon Art drugs became less and less effective on them, and finally they died of heart and lung failure.
The whole process took about two weeks. Giyuu hadn’t gone through any of those earlier stages. He shouldn’t have been in danger yet.
Shinobu instructed the girls to get hot-water bottles ready. Then she quickly prepared a dose of Blood Demon Art suppressant. Her fingers trembled as she injected it into his vein. She didn’t know if it was the medicine or sheer effort, but after working all night, Giyuu finally woke up around noon the next day.
He stretched, loosened up his joints, and seeing nothing felt off, he walked out.
Giyuu knocked on Shinobu’s door. When she opened it, he saw the bloodshot veins in her eyes and the dark circles beneath them.
“Shinobu, did you run into a tough demon last night?” he asked.
“No.” Shinobu rubbed her reddened eyes. “How are you feeling?”
“I’m fine. No problems at all,” Giyuu said. “Actually, I meant to say goodbye last night, but I forgot why I ended up staying an extra night.”
Shinobu pressed her fingers to her temples in frustration. “You went into sudden shock. Your heart rate dropped to 50 beats per minute. The Blood Demon Art concentration in your blood was three times higher than before, and your body temperature was extremely low. I honestly thought you wouldn’t survive the night.”
“But I did survive,” Giyuu said.
Shinobu took a deep breath and said helplessly, “Tomioka-san, you can’t leave yet. The fact that you even woke up is a medical miracle. No matter what, you can’t leave the Butterfly Mansion until the Blood Demon Art is completely cleared from your system.”
Giyuu thought for a moment and asked, “Kochou, so… can I have salmon daikon now?”
“No, you can’t.”
6.
In the following days, Shinobu had to draw blood once every hour. Since a swordsman’s hands were important, she chose to take the blood from Giyuu’s earlobe instead, leaving tiny red pinpricks all over it.
“Oh my, Tomioka-san, after treatment, maybe you can wear earrings on your ears like Tanjiro,” Shinobu mused, tapping her chin with a mischievous grin, “Previous patients all had bouts of wild mood swings. Honestly, I’ve been looking forward to seeing you go through fits of joy and sorrow too. Such an interesting Tomioka-san—I’d want to study you immediately.”
Giyuu clutched both his ears, gazing at Shinobu with a rather aggrieved, resistant expression.
Without the Water Hashira’s strength, the demon-slaying missions were even heavier than usual. Soon, Shinobu had to return to battle.
Before leaving, she instructed the children at the Butterfly Mansion that Tomioka’s Blood Demon Art concentration had dropped significantly these past two days, stabilising, but to be safe, they must still test his blood hourly. If an emergency arose, they were to send word at once and inject the potion she’d prepared in advance.
This time Shinobu went on the mission with the Wind Hashira. After a long night of bitter fighting, they finally cut off the demon’s head.
As the sky began to pale with the first light of dawn, she saw a messenger crow flying toward them in the distance, and her heart sank.
“Kochou Shinobu! Water Hashira Tomioka Giyuu is critically wounded! The medicine didn’t work! Hurry back to the Butterfly Mansion! Hurry!”
Sanemi shouted, “Hah? What’s going on with that damn Tomioka?”
Shinobu felt a throbbing at her temples. She turned at once and sprinted toward the Butterfly Mansion. “It’s a long story. Tomioka-san was hit by a Blood Demon Art—his condition’s unstable. Anyway, we need to get back as fast as possible.”
Sanemi caught up with her. “You’ve been fighting demons all night—can you even keep going?”
Shinobu said, “Shinazugawa-san, there’s no helping it. We’re Hashira. We always have to carry more.”
“How about this,” Sanemi said, rubbing his nose a little. “I’ll carry you on my back. I’m faster than you. You can rest a bit. That idiot Tomioka can die for all I care, but I don’t want to see Kanae’s little sister struggling.”
Shinobu froze for a moment, then smiled. “Then thank you very much.”
7.
Even with Sanemi’s help, by the time Shinobu rushed back to the Butterfly Mansion, daylight was already streaming in. She hurried into the infirmary in long strides. The girls there had done everything they could; when they saw her return, they looked at her as if she were their savior.
“You all did very well. Aoi, stay here and assist me. The rest of you go get some rest.” Shinobu placed her hand on Giyuu’s wrist. His pulse was still very weak.
“Aoi, what were Giyuu’s blood test results for the past hour?”
“It’s four times the normal level. We injected the medicine but couldn’t control it,” said Kanzaki Aoi worriedly, holding a tray.
“Go brew a bowl of wisteria decoction,” Shinobu instructed.
She also prepared a drug to increase his heart rate. Before injecting it, she tested the concentration of Blood Demon Art residue in Giyuu’s blood once more. To her surprise, it had dropped significantly.
Shinobu held Giyuu’s hand, sitting at his bedside, staring at him in disbelief.
She hadn’t even done anything yet—just rushed back and run one blood test. That was all.
A thought flashed through her mind. She set the syringe aside and simply held both of Giyuu’s hands in hers. Soon, color began returning to his face, and the chill in his hands slowly faded.
When Aoi came back with the medicine, Shinobu put a finger to her lips, signaling for silence, and had her set the bowl aside.
More than half an hour later, Giyuu opened his eyes.
He turned his head. The girl beside him was still holding his hand, apparently so exhausted that she had fallen asleep on the edge of his bed.
Giyuu tried to pull his hand back but hesitated, afraid of waking her, so he let her keep holding it.
Before long, Shinobu seemed to fall into a nightmare. Her brows knit tightly, and her body trembled. Giyuu had no choice but to wake her.
“Kochou, wake up. Kochou.”
She woke to find Giyuu watching her with concern, and suddenly her eyes grew wet.
“Giyuu-san, I’m so glad you’re okay.”
“Don’t cry. I’m fine,” Giyuu said. “Also, can you let go of my hand?”
Shinobu let go at once. “Giyuu-san, you had another episode yesterday, did you know? The good news is—I have some new ideas about your condition.”
“What is it?”
“I suspect the Blood Demon Art you’re afflicted with is connected to me,” Shinobu said. “You mentioned before that demon turned into my appearance, right?”
Giyuu nodded.
“This time, the medicine Aoi and the others used on you was the same as what I used last time. The only difference is that back then I was the one touching you. Same this time: when I came back and held your hand, your condition improved rapidly. Blood Demon Art isn’t something you can explain with common sense, so I’m guessing that physical contact with me suppresses the residual effect in your body—or might even eliminate it entirely.”
Giyuu immediately perked up. “How long do I need to stay in contact?”
“That I can’t guarantee. It’s only a hypothesis,” Shinobu said with a sweet, sly smile. “Last time, other girls did the blood tests for you, and I didn’t even see you for a whole day, but you were fine. Maybe even just meeting face-to-face has some effect.”
Giyuu suddenly clasped Shinobu’s hand earnestly, looking deep into her eyes.
A blush bloomed on Shinobu’s cheeks. Flustered, she stammered, “Eh? Eh? Giyuu-san!”
“So… can I hold Shinobu’s hand while eating salmon daikon?”
Shinobu didn’t stop smiling. She gripped his hand tightly in return and said gently:
“For the sake of your health—absolutely not♡~”
8.
“Shinobu, you just called me Giyuu-san, didn’t you?”
“I did no such thing.”
“I heard it.”
“You were hearing things.”
“Then can I call you Shinobu?”
“Do as you please, Gi-yu-u-sa-n.”
9.
After a week of testing, Shinobu reached a series of conclusions.
(1) Regular face-to-face meetings and skin contact can keep the concentration of the Blood Demon Art in Giyuu Tomioka’s body at a relatively low level, but neither can completely eliminate its effects.
(2) If they go more than 3 hours without seeing each other, the Blood Demon Art concentration in Giyuu’s body will gradually rise. After 12 hours, it reaches a level that causes shock. After 18 hours, his heart rate drops below 50, putting his life in danger.
(3) Both skin contact and simply meeting can lower the Blood Demon Art concentration in his body, but skin contact reduces it at 2.5 times the rate of just meeting.
(4) If meeting frequently is impossible, looking at a photo of the other person can also have a suppressive effect, but this method is only safe for up to 48 hours.
(5) The Blood Demon Art in Giyuu’s body is not impossible to eliminate completely, but it is extremely unusual and will require testing all 4,352 available medicines one by one.
Shinobu presented the experiment report to the Master, who said kindly, “You’ve worked so hard lately.”
Looking at the Oyakata-sama's gentle smile, Shinobu thought to herself that she’d rather die than tell anyone that in order to produce that report, she’d had to hold hands with Giyuu for two whole days—almost making eating, sleeping, and even going to the bathroom impossible.
10.
Giyuu was ready to return to battle again. Before he left, Shinobu tossed him a pocket watch.
“Giyuu-san, remember to check it often. Don’t go dying on the battlefield just because you weren’t paying attention—I still need to make you the antidote.”
Giyuu took it. Where the clock face should have been was a photo of Shinobu smiling. He hung the watch around his neck and said, “Thank you. I’ll look at it often.”
“Wait a moment.” Shinobu stepped forward, tucked the watch inside his uniform collar, and carefully buttoned it up for him one button at a time. “Don’t let anyone else see it. I don’t want people getting the wrong idea.”
Giyuu didn’t quite understand what she meant by “the wrong idea.” Tilting his head, he asked, “Is this okay now?”
“It’s okay now,” Shinobu said. “May you have good fortune in battle.”
“You too. Good fortune in battle.”
11.