Giyuu's ankle twinged, but he ignored it. It wasn't surprising. He'd had enough time earlier to heal it to a point where he could use it, but he had to keep an eye on it. Even reinforced, it wasn't as strong as normal, and running from a Waxing Moon level demon didn't help.

Despite that, it only added to the nostalgia of racing up the mountain he'd trained so long on. At least once he got past the 'running through the forest away from failures' part. It did feel a little strange to be going up the mountain while seeing many, many already tripped (or outright ruined) traps, even if he knew there could still be some active. He had to remain alert for those while keeping a steady pace, but he couldn't rush too fast, lest the demon behind him get bored and return to the house. If that happened, he'd have to cut his losses and just kill Rengoku Sr. He most certainly didn't want to – they'd lost too many people already – but if he had to, he would.

He'd only been running for a few minutes (that felt like hours) when the noises of the half-mad demon behind him faded. Giyuu paused and looked down the mountain through the trees that had already begun to turn colors for the season this high up in elevation. He saw nothing. Why had the demon stopped—

And then he remembered. The youngest two children had gone to hide up here.

No, he thought desperately as he took off in the direction he could now sense the demon moving. No, no no nononono! Due to his long years working as a demon slayer, he didn't panic, but it was a near thing.

He'd done this far too often. The unpleasant memories he'd managed to shove away before came rushing back at full force, hitting him almost like a fist to the stomach. He didn't let himself stop, though. Branches whipped at his cheeks because he couldn't go around thicker clumps of trees – couldn't afford the to waste even a second. He had to get there in time. He had to…

A scream from two boys echoed around the mountain.

Giyuu pushed faster and removed his sword. If he had to, he would kill Rengoku to save the kids.

He got to the right area moments later, sword aimed for the demon's neck… but Giyuu realized Rengoku stood frozen over the cowering boys, claws ready and mouth open, but… he wasn't moving. Had he remembered? Giyuu took in the scene in moments and had to make his decision. He decided to go for the torso instead. It would be awful for the children to witness that, but it might save Rengoku's life and give them a chance if he decided to continue attacking.

Before the Water Pillar reached him, though, Rengoku turned and raced back down the mountain, barely missing Giyuu's swing.

The black-haired man stopped and looked after the demon, confused. Then he looked back at the children, and after the demon again. That… that didn't make sense.

Eventually, though, he shook his head and crouched to follow his charge.

"Make your way back down the mountain," Giyuu said quietly to the children. "Be as quiet and aware as you can be."

He didn't stay to make sure the boys listened, instead taking off after the demon, keeping his senses alert for traps the entire time. He dismantled as many traps as he could without falling behind the demon to make it easier for the kids. All the while, he wondered what was going on. Was Rengoku going for the house again? If so, why? Why, when he'd had the children right there?

Much to his confusion, the former Flame Pillar didn't so much as glance over at the house as they passed it, not even with Sensei's body still sitting outside (he had to look away from that).

So where was Rengoku going?

Giyuu continued to follow the demon away from the mountain at a break-neck speed. He even frowned at not sensing his new Tsuguko's presence, but figured they had to have passed the boy by too quickly…

That didn't sit right with him, but he didn't have time to think on it.

For the moment, he contented himself with chasing the former Waxing Six through the surrounding forest. He'd figure out where they were going sooner or later, and then maybe Giyuu could get some answers.

xXx

Mitsuri hated this. She hated everything about their current situation. Here she and the other Pillars were, trying to hold the twisted form of one of the best men she'd ever met – one of the few men who could stand the thought of courting her – down while he thrashed and continued to turn into a demon. It felt like they'd been in the same position for years, not minutes or hours or whatever amount of time had actually passed. And worse, Obanai wasn't getting any better, continuing to try and swipe or bite at them…

"Obanai, please," she whispered to him, closing her eyes and willing her thoughts to reach him but not daring to move her hands lest he managed to break free. They had to get through to him. She honestly didn't care if he was a demon, as long as he was her Obanai. She had to make him see that! Once he could actually think, they could—

Then the ground near them, just outside what remained of the Ubuyashiki Estate Wall, exploded upwards, showering the area with debris. The demon slayers shrieked and all three Pillars looked over to see an enormous mound of earth, rock, and wood sticking out of the ground. She glanced at Kyojuro and knew he'd come to the same hard decision as her. If they were being attacked, they'd have to choose between letting Obanai go and potentially letting a mad demon loose, or killing him and fighting whatever had come to attack them.

Fortunately, before anything could happen, she looked back to see two figures being thrown from the great, upwards thrust of earth. One of them pulled their hands away from where the other's head should be… and the other was disintegrating.

What?

But then she recognized the first figure.

"Yushiro!" Mitsuri called out, incredibly relieved. Obanai tried to make use of their distraction and escape, but they weren't Hashira for nothing. They managed to keep hold of him.

The green-haired demon boy landed and rolled a couple of times on the dirt and weeds in front of the Estate before he got to his feet and looked around. A biwa hit the ground next to him. He snorted derisively before looking up and finding them.

"Kamado Tanjiro is fighting Muzan," he said, hurrying towards them. The other slayers around him all gasped.

"Who is this Yushiro?" Himejima asked.

"One of the demons helping us, I believe!" Kyojuro replied brightly.

"Yes," Mitsuri said, a little absently, eyes still focused on the demon coming towards them.

"The problem is," Yushiro went on, "he's gone berserk. I…" he paused, looking distinctly uncomfortable. "I've never seen him like this. We – the Ubuyashiki children and myself – aren't sure if he'll come back to himself once Muzan is finally dead."

"What?!" more than one person exclaimed. Mitsuri herself couldn't believe it. Tanjiro had always been so kind… He wouldn't do something like that! He wouldn't! Right?

Yushiro shook his head. "One way or another, we will be needed—" An explosion a fair distance away cut him off, making the ground shake. The demon slayers around them whispered fearfully.

"There," the demon finished. "We will be needed there."

Before anyone could answer, Mitsuri felt Obanai tense below her hands. He'd done that before, but this felt… different. She turned her eyes back just in time to see a green-and-yellow disk of energy shoot out from him, throwing the Hashira away.

No, not a disk… a hood. Like a snake's hood… that matched the color of the scaled skin around his neck, but from his whole body. He looked like a snake that had just flexed said hood out and… It was a blood art! He could use his blood art?!

Then he was gone, shooting off through the woods towards the explosion.

"Obanai!" Mitsuri cried and jumped after him.

"Everyone able to fight, follow!" she heard Kyojuro yell. "Those who can't, stay and help with the fire and first aid!"

"Be prepared to fight," Himejima said, voice sad but firm. She didn't know quite how he pulled that off, but she wasn't surprised. And… honestly, she didn't care. She could only focus on the disappearing form of her soon-to-be fiance pulling ahead of her. She pushed harder as she shot through the trees, feeling her neck pulse where the mark was. Well, so be it.

Just a few seconds later, they came across demons – obviously Muzan's demons – running (or in some cases, crawling) away from the general direction of the explosion. Mitsuri grit her teeth and unsheathed her sword. It whipped around her and she focused on her wrist movements and where she wanted the blade to go. She took down three demons in the blink of an eye and turned just in time to see Obanai stuff an arm into his mouth, pick up another screaming, pleading demon, and continue to run with it under his arm. It… made her sick. She didn't want to see him reduced to this…

But she also wanted to stand by him – to support him. No, she wouldn't give up on him. So she swallowed her disgust and pushed forward again, expression determined. Behind them, she heard more blades unsheathing and more breath styles used as the other demon slayers caught the lingering demons. Good. That meant she could focus on the Serpent Pillar. For some reason he wasn't focusing on pushing as quickly as before and she caught up enough to take off the head of the demon under his arm (Obanai had carried him backwards) and he cried in relief as his head went flying.

Obanai growled over his shoulder at her and picked up speed as the demon disintegrated. She could try and swing at him, but she couldn't bring herself to (not now, she couldn't give up on him) so she continued to follow him.

Not a minute later, they raced into what used to be a clearing, but now looked to be a miniature mountain – not smooth or round enough to be a hill, but sharp and uneven, with wood and paper sticking out of it at odd angles.

Obanai raced towards the two figures on top. The two figures who clashed in a terrifying display of power as a shock-wave hit her. It felt like slamming into a wall. She couldn't go forward anymore, stopping almost in mid-air and dropping to the ground. At least the blast also stopped Obanai as he thumped to the ground in front of her and… didn't move.

"O-Obanai?" she asked slowly.

"I…" he responded, his voice sounding harsh as he put a hand to his forehead. Then he turned to look at Mitsuri, slitted, mismatched eyes blinking at her as if he couldn't focus. "Mit… suri?" he asked.

She almost wanted to cry in relief. "Obanai!" She didn't rush forward to hug him. She didn't know if he was truly back or if this was a trick of some kind. If it was, she didn't think he'd do it on purpose, but better safe than sorry. Instead, she reached out to lay her hand on top of his, the one resting on the ground behind him, holding him up. He jumped at her touch and she took her hand back a little, before steeling herself and reaching out again. He watched as her hand went to hold his.

"Can't… think," he said. "Foggy."

Mitsuri nodded and crawled forward. "I'm not surprised."

He frowned at her. "What—"

Another shock-wave tore through the area, drawing both of their attention. Right about then, Mitsuri realized that they weren't getting the brunt of those power-waves. They would have to travel down the mountain to hit them at full force, not straight out or up and down. She could practically see where that power went, despite it not really hitting anything of consequence.

That… that was terrifying.

"Kamado?" Obanai asked.

Mitsuri bit her lip, but nodded, even though he wasn't looking at her. "Yes. That's Tanjiro."

The black-haired demon frowned. "Doesn't… look like him."

She had to agree there. It was him, but how he moved – wild and angry – looked like just about anyone but him.

"What… happened… to me?" the new demon inquired.

Mitsuri sighed.

"Wait… Waxing Third," he said suddenly and his eyes flew wide in realization. Also, the hood on his neck flared with his agitation. "No…"

"I'm so sorry, Obanai," she said as his hands found the scaled skin flaring out from the side of his neck and face.

He shook his head frantically. "No! Don't touch me! I—"

"You are not dirty, or unworthy, or any of the other disturbing things you were thinking about yourself!" she interrupted firmly, not letting go of his hand as he tried to pull away. "I don't care if you're a demon, I love you anyway!"

Or, well, she was willing to try. And even if it didn't work out for some reason, she'd still want to be his friend.

He blinked. "I… you what?"

She smiled, softly and warmly, because she needed him to know she meant it. However… "Maybe we should talk about this later and figure out how to destroy Muzan now?"

More blinking. Huh, his eyes had been beautiful before. Now they sparkled in the moonlight – almost glowing. Even with the slits, she could get used to them.

"The Love Pillar, not talking about love?!" Kyojuro asked loudly as he walked up beside them, grinning down. Then he focused on Obanai.

"I'm happy you've returned to us!"

"I…" he started, but the sounds of fighting above them stopping suddenly drew their attention. They all looked up just in time to see Muzan explode.

Tanjiro screamed.

xXx

"What's going on?! What's going on?! WHAT'S GOING OOOOOOONNNNN?!" Zenitsu shrieked, hands pulling the hair on the side of his head. For a moment he had been calm and cool and collected and then… well, everything had fallen apart. Again. He'd been blown back, as had both Inosuke and Kanao. Kanao had ended up in a bush, Inosuke tangled in several branches (cursing the entire time) and Zenitsu had hit a tree almost dead on, his back ramming into the wood painfully. Thankfully, he'd braced himself beforehand, reinforced his body with his breathing style, but still. There would be bruises. At least.

They'd also lost track of the demon boy. Kamado's younger brother? Where was he? Still crawling forward? Oh, wait… there he was running. They could catch up if—

Another blast sent them back and Zenitsu cursed. He wasn't the only one, though this time, his boar-headed friend managed to land a little better. Thankfully, all three of them managed to get back to their feet quickly.

"This is insane!" the Thunder Breather shrieked. Because, well, it was. The kind of power being tossed around here…

"Don't care! I ain't missin' out on this fight!" Inosuke said, breaking the branches he didn't have the patience to climb out of. Then he jumped down, landing next to Zenitsu, who stood up straight and turned to face him.

"Are you seriously going to go try and fight that?!" He wasn't even sure what 'that' was!

He expected Inosuke to rage or swear or scream or just stomp off. He didn't expect the boy to turn a hard stare on Zenitsu, made all the more surreal as he held his typical boar mask under his arm, absently clearing the fur from the sticks and leaves that had gotten stuck in it with his other hand… which still held one of his swords.

"Isn't that the main demon guy in there?"

Zenitsu frowned. "Well… yes."

"The Slayer Corps was made to take him out, right?"

The yellow-haired boy nodded slowly.

"Then why are we even waiting here? I ain't gonna let anyone else die if I can help it."

That was… surprising, actually. Zenitsu hadn't expected that from his friend at all.

"Yes," Kanao said as she joined them, eyes watching the mound of rock barely visible through the trees. "If we end it here, we end the demon threat permanently."

Supposedly. Zenitsu wasn't entirely sure he could completely believe that but… he'd like to.

"Are you coming?" she asked, turning to him. He blinked. Why were they even asking?

"Of course! I can't let you go in there alone! What would Nezuko-chan think?!" Besides, he actually liked his Slayer Corps friends and would like them to live.

Another wave of gale-force winds pushed them back a foot-length or so.

"We could die," the Flower Breather pointed out.

Zenitsu actually snorted at her. "I knew that the moment I picked up a sword." He managed a shaky smile. "Lightning breathers tend to pick things up fast."

Was it just his imagination, or was that a genuine smile on Kanao's face? Faint – almost imperceptible – but there.

"Okay," she replied, nodding. Another blast of air hit them, followed quickly by another. Once that died down, they looked towards the clearing again.

"Let's go!" Inosuke yelled, plopping the boar-head atop his own and holding one of his hands – along with his sword – in the air.

Kanao nodded. "Yes. But before we go," she turned to Inosuke, "I have a question: Did you know about that mark on your chest?"

Blinking, the black-haired boy looked down at the mark on his chest, the simplified boar-face breathing in and out. He frowned.

"How did that get there?" Before their eyes, he poked at it. It moved a little, but not in relation to his finger. It was still… weird. And a little creepy.

"That's a slayer's mark!" Zenitsu shrieked, pointing at it! "It limits your lifespan but gives you more strength! I'm sor—"

"Wait, this makes me stronger?!" Inosuke asked, grinning ferally.

"It does. In exchange for years of your life," Kanao said matter-of-factly.

"Who cares?! I'm stronger!" the boar-raised boy cackled.

Zenitsu groaned and dropped his head into his hand. "Of course that's what you take from this."

"Come on!" Inosuke said again, this time leaping into the trees. The others followed him. They reached what used to be the clearing just in time to hear Kamado scream.

"NO! NO! THAT'S HIM! FIND HIM! KILL HIM! NOW! EVERY SINGLE PIECE!"

Zenitsu frowned. He'd hoped what he'd heard before would change, but… it hadn't. That didn't sound like Tanjiro, despite it definitely being his voice. The offness – the demonic darkness – was still there. That deep hatred Zenitsu had heard underlying Tanjiro's melody every now and then – a disharmonious chord that threw his entire perception of the older Kamado off – now sounded loudly and angrily throughout the demon's body, pulsing with every beat of the boy's heart.

He'd heard it before, when he'd stopped the younger Kamado from going to his brother. It just sounded so… wrong. All that hatred where the boy had sounded so kind… it made Zenitsu sad. And more scared than he'd ever felt before.

Before he could say anything, though, Inosuke rushed forward, sword dicing a blob of… what was that?! Flesh?! Zenitsu leaned away in revulsion.

"What is THAT?!" he shrieked.

Kanao hadn't wasted any time searching out the slug-like substances herself. She also used her breathing forms to destroy them.

"Muzan," she said calmly.

If anything, that only made Zenitsu feel more disgusted. No, 'disgusted' didn't quite do it justice. Was there something worse than that? Stronger? Revulsion, maybe?

He both wanted to destroy what he could now see was an army of flesh-slugs while simultaneously not wanting something that gross to touch his sword. Or him. Or… be anywhere near him.

"Ronitsu!" Inosuke shouted!

Zenitsu looked down and saw one by his feet. HOW HAD THAT GOTTEN THERE?! He'd heard it but it hadn't sounded that close! Was he that distracted?

"GYAAAAAAAAAAAAA!" he screamed and stabbed his sword into the thing multiple times. Eventually, it disintegrated, thank the kami. He thrust his sword into the ground and just rested there for several seconds, breathing harshly, before he turned to the other two. They stood frozen, watching him. After a moment, Kanao nodded and went back to finding her own flesh-slugs. Inosuke gave him two thumbs (and swords) up. Zenitsu could just sense his manic grin as he also went back to destroying every demonic thing he could find.

Zenitsu groaned. He couldn't wait for tonight to be over.

Refusing to leave his friends alone, he made himself attack more of those creepy slug-things. He didn't know how long they sought the disgusting Muzan-pieces, but it felt like hours or days.

Finally, they got the last one in that area. He watched it disintegrate himself and found himself holding back his dinner when a light off to his left drew his (and everyone else's) attention. His eyes went wide as he realized what he was seeing: a wall of flame shooting towards them. He could have probably outrun it for a couple of minutes at least, but the wall just came so quickly, and he was so tired, he just couldn't seem to make himself move.

Oh. I'm going to die, Zenitsu thought as it rushed forward and engulfed him.

xXx

AN: NGL, I went through this at 1 in the morning, and am so tired rn... I'm not entirely sure I caught everything, and I made some changes but I'm not sure they flow, so if you see any issues, it's not my beta reader, it's totally me making last minute adjustments. Speaking of, thank you to Found and Quathis! :D

Discord: discord. gg/xDDz3gqWfy (no spaces)

Also, MERRY CHRISTMAS! Or Happy Hanukkah! Or Kwanza! Or whatever you celebrate! I hope it's amazing and wonderful!