Genya sat curled up in his box, knees tucked into his chest. His muzzle, gun, and family drawing sat next to him. He looked to the door of the box. It was probably still daytime out. Tanjiro or Nezuko would tell him if it was safe to leave.

He wondered what was going on. There was some new guy who called himself Zenitsu. His siblings had to go on some sort of mission, and they left him here. To protect some kids? And then the kids left.

“I don’t know what’s going on, but stay safe, all of you.”

~~~

Nezuko chased after the cackling kid with the boar head, unsheathing her blade at the same time. Her instincts were right; the presence of the demon was certainly getting stronger. Following this stranger was the right choice.

“COMIN… THROUGH!”

The boar head leapt through a window, tearing the paper covering. Nezuko gritted her teeth in frustration. As accurate of a guide he was, he was also too unpredictable. Without much choice, she jumped in after him.

Her body slammed into someone else’s, and they both fell to the ground. It was the boar headed boy.

“Nezuko!”

Tanjiro’s voice came from up ahead. Nezuko looked up to see her brother, holding a terrified Teruko.

“Onii-chan!” She yelled back. “Are you-”

The stranger shoved her off with a roar of frustration.

“OUTTA MY WAY!” He yelled. Nezuko stilled as he pointed one of his jagged blades in her direction.

“What are-” Nezuko swiftly stumbled back, collapsing on her still unhealed foot as the boar swung his blade at her.

“What are you doing?!” Tanjiro yelled, fury taking over him. “We’re allies here!”

“So… annoying…”

The new voice finally brought Nezuko’s attention to the very front of the room. A demon stood in the doorway, nothing but red in his eyes. Tsuzumi drums were attached to his legs, arms, and stomach.

“So that’s where the drumming came from.”

The demon struck the tsuzumi on his left arm. The pang of the drum rang out through the room. In an instant, Nezuko found her feet swaying as the room tilted. Each of them fell over, Tanjiro doing his best to shield Teruko while the boar continued to cackle.

“THE ENTIRE ROOM JUST SPUN AROUND! FUN! SO FUN!”

“Concentrate!” Nezuko called, steadying her blade and directing her gaze at the demon’s neck. “Breath of Flames, First Form: Unknowing Fire!”

She lunged forward. The demon struck the tsuzumi on his left leg, and Nezuko found herself flying back as the room spun backwards. She landed on her back and suppressed a groan of pain.

The boar charged forward next, wielding both blades over his head. His maddening laughter filled the room.

“How… irritating…”

The demon hit the tsuzumi on his stomach. The sound of the floorboards tearing reached Nezuko’s ears, and she dived to the left. Just in time to see three claw like gashes run through where she was a mere moment ago. The boar also managed to evade, stumbling and swaying on his feet. Tanjiro leapt to the side, clutching Teruko close to his chest.

“Every time he hits one of the tsuzumi, something new happens. Does each action correspond with a certain drum?”

The demon tapped the drum on his right leg, then the one his left arm, then the stomach.

The room spun and Nezuko lost her balance again. Even if she could learn the pattern, it would be difficult to move with the room’s changes without falling over. She barely evaded the claw attack, the ends of her haori getting grazed and torn.

She glanced around. Tanjiro seemed to be preoccupied with protecting Teruko, and the boar guy was too much of a wildcard to rely on any more.

It was up to her.

She had to do it. To protect Teruko and find her big brother, to reunite with Zenitsu and make sure he was okay, to get back to Genya. To protect everyone she cared about, she needed to slay this demon.

“Breath of Flames, Fifth Form: Flame Tiger!”

She dashed forward, swinging her blade harshly down towards the demon’s neck.

The pang of the tsuzumi, rotating the room forward. Nezuko lost her momentum as she tried to scramble back to her feet.

“Nezuko!”

Her brother’s desperate cry was drowned out by the pang of the tsuzumi on the demon’s stomach. Nezuko tried to roll to the left, but the claw attack reached her, leaving deep grazes on her right calf. She bit down a scream.

“Need… marechi… not you…”

“Nezuko!” Zori clattered across the tatami floor as Tanjiro ran towards Nezuko, still holding a teary eyed Teruko close.

The boar was still cackling. “MY TURN NOW!”

His attack failed to reach the demon, too. As Nezuko tried to struggle to her feet, the demon struck the tsuzumi on his right arm, rotating the room to the right. Nezuko found herself falling in a heap with Tanjiro and Teruko, while the boar was knocked into another room.

“Nezuko, look after Teruko,” Tanjiro said, getting to his feet and standing protectively in front of both of them.

Before either of them could react, the sound of a tsuzumi rang through the air.

The demon vanished from sight.

“Huh?” Nezuko seethed, sitting up. “Where did the demon go? Are we… in a different room?”

“This is exactly what happened the first time we got separated,” Tanjiro said, looking around. “It looks like the people who were in the same room stay together, which is why that boar and the demon aren’t here.”

Teruko sniffled. “M-miss, are you okay?” She asked, eyes focused on Nezuko's leg. The purple hakama pants were darkened where the gashes cut her.

“I’ll- be fine,” Nezuko said, using the wall to help herself up. “It’ll heal soon enough.” She forced herself to smile through the pain, to reassure Teruko that she was okay.

“That demon didn’t hit a tsuzumi when we were transferred here,” Tanjiro said. “I had a clear look at him, I would have seen. So, are there multiple demons with tsuzumis?”

Nezuko turned her head, trying to attune her senses. “I’m sensing multiple demons, but that one was definitely the most powerful. Your smell picking up anything?”

Tanjiro sniffed the air. “Blood, I think. Something sweet, too.”

He looked towards Teruko. “For now, let’s just move. Teruko, stay close to us.”

The girl nodded. Tanjiro carefully looped one of Nezuko’s arms over his shoulder to help her walk.

“We’ll need to patch this up,” he whispered. There was a hard edge to his voice. “We still have some supplies from Tamayo-san. So we’ll wrap your leg up as soon as possible.”

Nezuko nodded as she limped. “I can sorta walk, but I don’t know if I’ll be able to move fast enough to get the demon’s head. Especially if he’s going to rotate the room like that.”

She hung her head. “I’m sorry for failing.”

“It’s okay,” Tanjiro assured her. “You did your best. Now, let onii-chan take care of the rest.”

They walked towards the sliding door at the end of the room they found themselves in, Teruko clinging to the edge of Tanjiro’s haori. Tanjiro, in the front, carefully opened the door. Nezuko saw him blanch and grimace. She could only assume he found another corpse.

“Just how many people did this demon kill? It makes me sick. Unforgivable. Completely unforgivable.”

“Tanjiro onii-chan, what is it?” Teruko asked, clutching at his checkered haori.

“N-nothing,” Tanjiro lied through his teeth, trying to put on a brave face for the terrified girl. “It’s nothing. Just… stay close to me. And don’t look back.”

He led them through the hallway. Nezuko could smell the putrid scent of blood against her nostrils. It made her feel ill. It must have been even worse for Tanjiro.

“There’s a strong scent of blood up ahead,” Tanjiro said.

“So a lot has been spilled?”

Tanjiro shook his head. “Based on the smell, the wounds aren’t that deep. It’s something about the blood itself that makes it different. It’s odd. I’ve never smelled anything like it before.”

He came to a stop, the two girls halting along with him. They stood in front of another door at the end of the hall they just walked through.

“It’s there,” Tanjiro said, pulling the door open.

In front of them lay another hall, which led to a room with an open door. A boy in an orange kimono sat in the center, clutching a tsuzumi to his chest. When they locked eyes, fright overcame the boy’s features, and he raised his hand to bang on the drum.

“Kiyoshi nii-san!”

Teruko tore herself away from Tanjiro, running to the other boy before he could strike the tsuzumi. Recognition flitted across his face, and the boy beamed as he wrapped Teruko in an embrace.

Tanjiro and Nezuko came closer. “You must be Kiyoshi, Teruko’s big brother,” Tanjiro said. “I’m Tanjiro Kamado, and this is my little sister Nezuko. We came to defeat the demon.”

The boy’s face sagged in relief. “Wh-where’s Soichi?”

“One of our other friends is looking after him,” Nezuko assured him. “Let’s see your wounds.”

A few tears slipped from Kiyoshi’s eyes. He started sniffling as Teruko hugged him tight. Tanjiro pulled out some ointment from his uniform. “Here, let me see your leg.”

Tanjiro rubbed the healing ointment on Kiyoshi’s injured leg, whispering reassurances the entire time. “There, that’s better, right?” He asked, pulling a bandage over the leg. Kiyoshi sniffled and nodded.

“If it’s not too much, can you tell us what happened?” Nezuko asked.

“Th-that monster-” Kiyoshi stuttered out. “He- snatched me up and dragged me here. But then, two other monsters showed up, and they started fighting… over who gets to eat me.” He paused and hiccupped. “Then, the monster- the one with the tsuzumis, when he was struck in the back, one of the tsuzumis fell. When I picked it up and hit it, the room changed. I’ve been… using it to get away any time someone tries to get near me.”

Nezuko bit her lip. So there were still multiple demons in the house. She hoped that nothing bad would come because of them. Maybe the boar kid would kill them in his bloodlust. Or Zenitsu might pull himself together.

“You’ve done a very good job,” Tanjiro said, patting Kiyoshi’s shoulder. His lip puckered up, brows furrowed in thought. “When we were fighting him, he mentioned something about marechi, or rare blood.”

Kiyoshi nodded his head vigorously. “I heard that, too. He called me a marechi.”

“But what could he mean by rare blood?” Nezuko asked. “Maybe it has some special properties that make it extra nutritional?”

“I don’t think that matters right now,” Tanjiro said. “All we know is that Kiyoshi seems to be the demon’s main target. We have to protect him.”

“So, what’s the plan?” Nezuko asked.

Instead of answering, Tanjiro stilled, his features tensing up in fright and anticipation. Nezuko could hear thunderous footsteps nearby. The demon was getting close.

“I’ll go fight him,” Tanjiro said. “Nezuko, stay here with Kiyoshi and Teruko. If anyone comes here, hit the tsuzumi and get away. If anyone manages to get in, Nezuko will protect you.”

“But, I can help you fight-” Nezuko tried to insist.

“Your leg is still bleeding,” Tanjiro interjected. “Keep the ointment. Treat it. And protect them if it comes to it.”

Nezuko grit her teeth. “Okay,” she said after a moment. There was no time to argue. The demon was peeking out through the far doorway. He had spotted them.

“I’ll find you by scent after I defeat him. I’ll call out your names so you know it’s me. Get ready.”

Tanjiro gripped his blade and dashed out. “Strike it now!”

Kiyoshi slapped his hand on the drum, and Tanjiro vanished from view.

“Uh, Nezuko nee-san…” Teruko tugged on her sleeve. “Your leg… do you want some help putting the ointment on?”

Nezuko smiled. “That’s very kind of you, Teruko. Please.”

Teruko picked up the cream while Nezuko wrapped her fingers around her blade.

“Stay safe, onii-chan,” she said to herself. “Stay safe for me.”

~~~

Tanjiro found himself face to face with the tsuzumi demon. The demon that hurt and killed so many people, the demon that had terrorized Kiyoshi and his siblings, the demon that hurt Nezuko.

He glared and raised his sword.

“Insects… damn pests…” The demon muttered, striking the tsuzumi.

The room began to shift and rotate. Tanjiro did his best to keep up with the changes with his broken ribs. He grimaced, shifting his balance between his legs in rhythm with the rotations.

Even after he learned which drum corresponded with which rotation, it was hard to keep up with the tsuzumi strikes. While this demon was among the more passive he has encountered, he clearly had the most innate power. Tanjiro knew that one slip up could easily cause him to be minced into sushi. He grimaced at the thought.

He gritted his teeth. “Stay strong, Tanjiro. For Nezuko! For Genya! For Zenitsu! For Kiyoshi and Soichi and Teruko!”

He raised his blade higher. He remembered his training.

“Water can take on any form,” Sakonji had told him. “Breath of Water is the same. It can take on any form, defeat any opponent.”

“I’ve got this!” He yelled, more as a way to cheer himself on. “I’ve gotten this far, and I’ll go even farther! Even if I feel broken, I’ll keep moving forward!”

He charged forward. The room shifted to the left. Tanjiro swiftly moved with the rotation, like water flowing down the river. His ribs and chest ached. It was hard to breathe, but he couldn’t afford to give up now. Not after the declaration he just made.

“Demon! What is your name?”

The demon seemed startled by the sudden question, his hand faltering over the drum. “Kyogai…” he said after a moment.

“Kyogai! I won’t let you hurt Kiyoshi - the marechi - or anyone else! I’ll cut off your head for sure! I won’t give up!”

If Tanjiro’s first statement had stunned Kyogai into confused inaction, this one had fueled his previously unseen rage. He roared.

“I will eat the marechi, and reclaim my place among the Twelve Demon Moons!”

When Tanjiro looked into Kyogai’s eyes, the previously red sclera had been replaced by a blue iris. Two scars ran through it in a painful X pattern, the kanji for Lower Moon Six barely decipherable beneath the marks.

“This demon used to be a Moon? So he really is the strongest I’ve faced so far.”

The room was spinning rapidly now. In his rage, Kyogai was striking the tsuzumi at a far faster rate. Tanjiro’s eyes hurt as he grew dizzy. Each breath he took hurt his chest and made his broken ribs ache. The room rotated so fast he never even hit the ground, just spinning endlessly in midair.

Tanjiro swerved as a gust of air blew past him, just in time to see five claw marks run through the ceiling above him. Five now, not three. This was bad.

Another rotation to the right, then forward, then back, then right, then forward again. Tanjiro struggled to keep his grip on his blade. Papers filled his vision as the cabinets in the room started turning and opening. They were tumbling out over the floor and walls. Something was inscribed on them. Stories, maybe song lyrics? Tanjiro had no time to dwell on it. He swiftly landed, making sure to avoid stepping on the papers. He breathed shallowly, his body tired and drained of energy.

“That’s it.”

Shallow Breaths. Shallow Breaths wouldn’t exacerbate his wounds. If he could Breathe shallowly, he could get close to Kyogai without stumbling from the pain.

Kyogai wasn’t attacking. Was that shock on his face? Tanjiro readied his sword.

“Breath of Water, Ninth Form: Splashing Water Flow- Turbulent!”

Shallow Breaths, light jumps. This form was made to minimize landing time, allowing him to move quickly in accordance with the rotations. Seeing Tanjiro moving in to attack, Kyogai started to strike the tsuzumi again, but he was clearly too late.

“Kyogai! Your Blood Demon Art is incredible!”

The demon hesitated again. Tanjiro closed in, slicing his sword through his neck. The decapitated head fell to the floor. Tanjiro landed, breathing heavily.

“No no no, shallow breaths. Shallow.”

Tanjiro stumbled to his feet. This was… a powerful foe. He’d be a fool to deny it. If he could get some of his blood to Tamayo, it would probably help with the cure. He fished out one of the knives Yushiro had given him and flicked it in the direction of Kyogai’s body. The container within turned red from the blood.

“It really does work. Amazing.”

Tanjiro plucked up the knife as the sound of a meow reached his ears. He turned around and saw a cat with a basket on its back. He recognized it from Tamayo’s house, and it was wearing one of Yushiro’s talismans.

“Are you here to take this to Tamayo?”

The cat seemed to nod. Taking this as a yes, Tanjiro opened the basket on the cat’s back and slid the vial into it. After he tugged it tight, the cat vanished with another meow.

“How convenient…”

“Boy…” Tanjiro turned around. Kyogai’s disembodied head was slowly turning to dust. “Did you mean it? Do you really think my Blood Demon Arts were incredible.”

Tanjiro sighed. “They were amazing. It was some of the best tsuzumi playing I’ve ever heard. But… I cannot forgive the murder of innocent humans. And you hurt my little sister.”

“I see… I thought so…” Kyogai seemed to be taking his death in stride, almost resigned to his fate. Tanjiro could smell the sadness rolling from him in waves. Was he also a demon that suffered?

“Rest in peace,” he said, putting his hands together in a short bow.

“Next time, Gods, please treat him with a bit more kindness. Allow him to remain a human, and use his tsuzumi playing for good. In his next life, don’t give him the misfortune of becoming a demon.”

Tanjiro left the room with a final bow, leaving Kyogai to turn into wisps of smoke.

“Nezuko! Kiyoshi! Teruko!” Tanjiro yelled out. He could detect their scent up ahead. This was good, he was close.

“Nezuko!” Their scent was coming from the door up ahead. Tanjiro flung it open, only to be met with a sword to his neck.

“Eh! Nezuko!”

“Onii-chan!” Nezuko dropped her weapon, wrapping him in a hug. “The tsuzumi vanished, so we all got a bit jumpy. I’m so sorry!”

“It’s fine, it’s fine,” Tanjiro assured her. “That’s good, you were trying to protect Kiyoshi and Teruko.” He could now spot the two children cuddled fearfully behind Nezuko. “How’s your leg?”

“Better now that we applied the ointment,” Nezuko said. “You? Any injuries?”

“Nothing I didn’t have before.”

Nezuko looked over his shoulder. “I also stopped sensing the presence of the other demons a little while back. Did they also vanish when you defeated the main one?”

Tanjiro’s brows furrowed. “I don’t think so. If that were the case, they would have been working together. Someone else must have defeated them. Zenitsu, or the guy with a boar head.”

“Anyways, let’s get these two out of here.”

Tanjiro bent down. “Kiyoshi, if you’re still tired, I can carry you on my back.”

Kiyoshi’s lip puckered a little, as if he was on the verge of tears, and carefully climbed onto Tanjiro’s back. “Thank you, Mister.”

“Let’s get out of here and get you to Soichi,” Tanjiro said, leaving the room with Kiyoshi on his back. Teruko trailed after him with Nezuko in the rear.

“We’re going to need to bury all these people,” Nezuko murmured, the scent of blood still weighing heavily on her.

“I know,” Tanjiro said. “So much death, and for what? It’s… truly unforgivable.”

So this is what a demon was capable of when they bore killing intent. So much carnage caused by one singular being. Is this something that Genya could have become if he hadn’t snapped out of it? The thought was too terrifying to dwell on.

They had almost reached the exit of the building when Tanjiro abruptly stopped, the smell of blood hitting his nostrils.

“What is it, Tanjiro nii-san?” Teruko asked.

“N-nothing,” Tanjiro said, walking forward again. His face was tense with apprehension. What could be awaiting them outside?

“COME ON! DRAW YOUR SWORD AND FIGHT ME, YOU COWARD!”

Zenitsu desperately clung to the box with Genya inside, his face covered in bruises and blood. The kid with the boar head stood over him with his blades drawn.

“FIGHT BACK, YOU SPINELESS PUNK! OR I’LL SKEWER YOU ALONG WITH THE BOX!”

“I won’t let you!” Zenitsu yelled back. One of his eyes was almost swollen shut. Soichi cowered behind a tree with tears in his eyes. “I won’t let you do anything to the box until Tanjiro or Nezuko-chan get back! They said it was more important to them than their life!”

“Zenitsu…” Tanjiro could feel something within him snap, seeing the boy in that condition.

Zenitsu looked up at the sound of Tanjiro’s voice. “I protected it, Tanjiro…” he whimpered. “I protected it.”

The boar was not deterred, adjusting his grip on one of his blades. “That’s enough from you.” This time, his voice was lower. It was somehow more threatening than his thunderous shouts. “You had your chance. Now, move aside!”

“Shut up, both of you!”

The final shout came from the box.