Blood Demon in Demon Slayer - Chapter 3

Chapter 3 — Territory

Boredom, Rai decided, was criminally underrated as a form of suffering.

He had been awake for approximately six hours. He had not moved from the hollow at the base of the cedar tree. He had counted the visible branches overhead — forty-three, give or take the ones that overlapped and made counting ambiguous. He had listened to every bird in a two-hundred-metre radius establish its morning opinion at full volume. He had watched a beetle navigate the root system beside his left knee with the focused determination of something that had somewhere important to be.

He had thought about every episode of Demon Slayer he had ever watched, in chronological order, with commentary.

He was losing his mind.

The thing nobody mentioned about becoming a demon — or rather, the thing that got significantly less screen time than the blood and the tragedy and the magnificent sword choreography — was that demons apparently didn’t sleep. He had known this, technically. He had filed it under ‘facts about the setting’ the way you filed information you understood but hadn’t yet felt.

Demons had too much energy. Their bodies ran hot, or whatever the demon equivalent of hot was, a constant hum of something that wasn’t quite electricity but functioned similarly, and that hum didn’t stop because the sun came up. It just had nowhere to go.

Rai had nowhere to go either.

He tried, at about the three-hour mark, out of sheer stubbornness. Closed his eyes. Regulated his breathing. Performed every trick he’d learned during long hospital nights when sleep refused to come — counted backward from three hundred, relaxed each body part individually starting from the toes, tried to empty his mind of everything except the texture of the bark against his back.

His mind filled immediately with a precise and detailed inventory of every problem he currently had.

He gave up and went back to the beetle.

—

Around midday — he was guessing, but the light filtering through the canopy had reached its flattest, most vertical angle — boredom curdled into something more experimental.

He looked at his left hand.

He looked at the thin strip of light that came through a gap in the canopy overhead, falling in a narrow column about a metre to his left. Thin. Barely anything. The kind of light that in any other context you wouldn’t even call sunlight, just a reminder that sunlight existed somewhere above a great deal of leaf.

He looked at his hand again.

‘Don’t’, said the sensible part of him.

The sensible part of him had also spent three hours trying to sleep and failed. Its credibility was currently limited.

He extended one finger — the index finger of his left hand — and moved it slowly, incrementally, toward the column of light.

The first thing he noticed was the warmth. Not comfortable warmth. The warmth of something that was about to become a problem, registering in the skin before the actual damage began, a preliminary warning that his nerve endings sent up with what felt like genuine alarm. ‘Sir. We have concerns. Sir, we really must—’

Then the tip of his finger crossed the threshold.

The pain was instant and total and shockingly specific — not like burning your hand on a stove, not like the diffuse heat of a bad sunburn. More surgical than that. Like the light had decided, with great precision, to simply ‘disagree’ with the biology of his fingertip. He yanked back on instinct, which was probably the right call, and stared at what remained.

The first centimetre or so of his index finger was gone. Not burned — ‘gone’. The edge of what remained wasn’t charred or blistered. It was just the boundary where his finger had stopped, clean as a cut but without a cut, a precise line where Rai ended and ash had been a moment before.

He stared at it.

He stared at where the ash had scattered across the root beside him, grey-white, already dispersing in the faint movement of air through the forest floor.

‘That’, he thought, with great clarity, ‘was part of my body.’

The regeneration started almost immediately — he could feel it, a strange knitting sensation at the truncated tip, slow and deliberate, like watching time-lapse footage of something growing. Slow. Much slower than it would have been in the dark. The sunlight in the air around him, even indirect, even filtered through forty-three branches and several hundred leaves, was apparently enough to put a significant drag on the process. A Hashira could take a limb. Out in open daylight, he probably wouldn’t be growing it back at all.

He tucked both hands back into the shadow of the hollow and sat with this information.

Sun. The nemesis. The thing that even Muzan — the man in the black suit, his ‘God’ — had spent centuries engineering around, running from, building strategies to eliminate. The Demon Slayer Corps existed specifically to fill the hours of darkness. Every Upper Moon, every piece of architecture in demon society, every decision about territory and timing and method — all of it, ultimately, in service of the single question: ‘how do we survive until the sun goes down again?’

And Rai was level thirteen with a stat spread of one across the board. A level thirteen demon who had spent his previous existence watching this universe from a hospital bed and now had the temerity to be sitting in it.

He pulled up the panel. If he couldn’t sleep and couldn’t move and couldn’t do anything productive with his body, he could at least think.

—

Demon: Lv13 (45/105)
Blood Demon Art: [Locked]

…

HP: 130/130 | BP: 130/130
STR: 1 | AGI: 1 | VIT: 1 | SEN: 1 | BC: 1
Free Stats: 60

—

Sixty points.

He read the stat categories again, and this time he wasn’t reading them as abstract numbers. He was reading them as a threat assessment.

‘STR — physical attack power.’ How hard he hit. Not nothing, but not what was going to keep him alive.

‘AGI — speed and reflex.’ How fast he moved. How quickly he reacted. The difference between a blade hitting him and a blade cutting air where he used to be.

‘VIT — durability and regeneration.’ How much punishment the body absorbed before it became a problem. How quickly it repaired afterward.

‘SEN — perception and combat instinct.’ What he noticed. How much of the world resolved into information before it resolved into a fist or a sword. The difference between knowing an attack was coming and finding out about it from the wound.

‘BC — Blood Capacity.’ The energy pool for Blood Demon Art. Locked. Useless until it wasn’t.

He sat with them. Not thinking about what he wanted — he’d had enough conversations with his own wants to know they weren’t always reliable advisors. He thought instead about what was going to try to kill him.

Demon Slayers.

That was the primary threat. The Corps moved at night, same as demons, because that was when demons moved. They carried Nichirin blades — swords that held sunlight in their ore the way wood held smoke, that could kill a demon the way nothing else could except the actual sun or complete destruction. They were fast. Inhumanly fast, by human standards, their Breathing techniques compressing and accelerating their physical capabilities into something that could match or exceed a demon’s natural advantage.

Rai thought about the fights he’d watched. Thought about Zenitsu’s speed, Inosuke’s instinct, Tanjiro’s ability to read the shape of an opponent’s next move before it happened. What had made those fights terrifying, from the demon side, wasn’t power. It was ‘speed’, and the instinct to use it correctly.

And on top of speed — ‘sense’. The ability to read the air of a fight, to know where the sword was going before the sword committed to going there.

Running was the first priority. He was honest with himself about that, in a way that didn’t bother him much.

He had spent eight months dying slowly in a hospital bed. He had no illusions about his own heroics. Survival was the operating principle. Survival first, everything else later, and the things that served survival were the things worth building toward.

He didn’t need to win fights right now. He needed to ‘not be in them’.

For that, he needed to be faster than what was coming. And he needed to know what was coming before he could see it.

He allocated the points.

Thirty into AGI. Twenty into SEN. Five into STR, because being able to move something out of his path was different from being able to hit it, and there was a minimum of physical presence required just to interact with the world. Five into VIT, because regeneration speed mattered, and a little more durability meant a little more margin for error.

Nothing into BC.

Not yet. No point building a pool for something he hadn’t unlocked. That was the resource management equivalent of filling a bucket with a hole in it and feeling productive.

He confirmed the allocation.

And then the world changed.

It didn’t change visually — the forest looked the same, the same forty-three branches, the same beetle who had apparently completed one lap of the root system and was beginning a second. But the ‘resolution’ changed. The depth changed. Everything that had existed before as general information — the bird sounds, the movement of air, the specific pressure of bark against his spine — suddenly sharpened into data. Individual, precise, layered data, arriving not as noise but as a kind of map, continuous and detailed and ‘alive’.

He could hear a spider building its web six metres away. Not as a sound — as a distinct, specific vibration in the air, separate from the branch movement and the distant creek and the birdsong and the rustling of something small and mammalian in the undergrowth to the north-northeast. It wasn’t louder. It was ‘clearer’. Like someone had turned up the resolution on a screen without changing the screen size.

He breathed, and his own breath came back to him with information. Humidity. Decomposition. The faint mineral bite of the creek he’d clocked at some distance north. Something that might be smoke, far away, probably a village. The forest, in layers, each layer distinct.

His eyes tracked a leaf as it detached from a branch twelve metres overhead and began falling, and he watched it travel and could calculate — not with math, just with something new and instinctive — where it was going to land before it landed there.

‘Oh’, he thought. ‘This is what SEN actually means.’

He pulled up the final panel.

—

Demon: Lv13 (45/105)
Blood Demon Art: [Locked]

…

HP: 130/130 | BP: 130/130
STR: 6 | AGI: 31 | VIT: 6 | SEN: 21 | BC: 1

—

He closed it, and sat back, and felt the afternoon pass around him with a new precision that made it, if not enjoyable, at least interesting. The forest was full of things. He had simply not had the instrumentation to receive them before.

When the light finally began to angle, and the patches of sky visible through the canopy shifted from white-blue to the deep, saturated blue of pre-dusk, something in his body settled. The alarm that had been running at a low frequency all day quieted. The hum of trapped energy found a direction.

He stood, unfolded himself from the hollow, and walked.

—

The forest received him without comment.

He moved north, away from the factory, away from the direction the creek’s smell suggested a settlement might lie, away from anything that sounded like human habitation. He was thinking about what he’d watched in those hospital-bed sessions — the way demons maintained territory, the way the ecology of this world’s supernatural community worked, the invisible maps carved up in blood and violence across the landscape.

He was thinking, specifically, about the fact that he was standing in someone’s territory right now and had no idea whose.

He was also thinking about animals.

The question of animal blood had been nagging at him since he’d stood outside the factory that morning. It was a reasonable question. A practical question. The kind of question a person asked when they were trying to find a route between ‘I need blood to survive’ and ‘I would prefer not to hurt people’.

An answer would be good. An answer would be—

He felt it before he heard it.

The SEN stat resolving something at the edge of his range — a presence. Moving. Bipedal, probably, but with a weight distribution that wasn’t quite right for a human, slightly too distributed, slightly too low to the ground, the gait carrying a quality of someone who had been moving through forest for a very long time and had stopped bothering to move like anything other than what they were.

Demon.

The certainty arrived without drama, the way cold arrived when you stepped outside. Just a fact. A registered fact.

Rai slowed. Then stopped. Then turned, carefully, toward the direction the presence was coming from.

Whoever it was came through the underbrush with no particular effort to be quiet — not aggressive, not rushing, just moving through their own space in their own time. A figure emerged from between two large pines about twenty metres away and stopped when it registered Rai.

In the dark, Rai’s new eyes resolved the details easily. Male. Young-looking, the way demons always looked young, but with something behind the eyes that didn’t match — something that looked at the world the way you looked at something you’d grown too tired of to hate anymore. Thin. The thinness of someone running on nothing, not the thinness of youth. Clothes that were old in the way things became old when nobody replaced them for a very long time.

For a moment they just looked at each other.

‘Okay’, Rai thought. ‘Another demon. Fine. Maybe we can—’

The figure moved.

Not fast — not with the compressed violence of someone with high AGI — but with the sudden, lurching desperation of something that had been starving for a very long time and had finally, finally found something that smelled like food. A sound came out of him that wasn’t quite human and wasn’t quite animal, something that lived in the register between grief and need, and then he crossed the twenty metres between them and Rai was already moving.

He didn’t think about it. His body moved before his mind finished processing the threat — AGI and SEN doing exactly what he’d bought them to do, the attack arriving as information ‘before’ it arrived as impact, and his feet already carrying him sideways and back, the reaching hands closing on empty air where he’d been half a second before.

“Hey — wait—”

The figure didn’t wait. He came again, faster this time, and Rai sidestepped again, and the movement felt clean — cleaner than anything his old body had ever managed, cleaner than anything he’d earned, and he was aware of that unfairness even while being grateful for it. He caught the figure’s arm on the third lunge and redirected the momentum rather than opposing it, shoving him sideways into a tree trunk with enough force that the wood cracked slightly.

The figure hit the tree. Slid down it. Sat on the roots, breathing hard.

The desperation in the sound of his breathing was almost worse than the attack had been.

Rai kept his distance and waited.

Slowly — like a tide going out, like pressure releasing — the wildness in the figure’s eyes receded. Left behind it something older and quieter and, Rai thought, significantly more sad.

The figure pressed the back of his hand to his mouth. His shoulders pulled inward. He sat like someone who had just done something they’d promised themselves they wouldn’t do and were now living in the moment after.

“I apologise,” he said. His voice was low. Formal, in the careful way of someone who had spoken to very few people in a very long time and still remembered how to do it correctly. “I haven’t eaten in a while.”

Rai stared at him for a second.

“How long,” he said, “is ‘a while’?”

The figure glanced up. Something flickered in his expression — not quite amusement, but the distant memory of what amusement had felt like before everything else had happened to him.

“Several months,” he said.

“Months.”

“I don’t eat humans,” he said. It came out flat. Not proud — there was no pride in it. Just a fact, stated with the weariness of someone who had repeated it to themselves enough times that it had worn smooth. “I hunt animals. But the animals in this forest have had two hundred years to learn my patterns. They’re better at avoiding me than I am at catching them.”

Two hundred years.

Rai looked at him properly. Sat down, cross-legged, on the forest floor, which he had learned in the last several hours was a perfectly reasonable place to sit. “Two hundred years,” he said. “You’ve been in this forest for two hundred years.”

“My name is Haruto,” the figure said. He said it like a formality, or maybe like a reminder — to himself as much as to Rai. ‘This is who I am. This is the name I have. I still have a name.’

“Rai,” Rai said, because that was the name this body came with and right now it was the name that was safest to use.

Haruto looked at him with the patient, measuring look of someone who had been alive long enough to tell a great many things from very little information. “You’re new,” he said.

“Very.”

“Last night?”

“Yes.”

Haruto nodded slowly. He looked at his own hands. They were the hands of someone who had been a farmer once — Rai didn’t know how he knew that, whether it was the SEN stat reading micro-details he wasn’t consciously processing, or just inference, but the knowledge arrived and settled. Work-worn. Patient hands.

“Then you’ll want to know how things work,” Haruto said.

It wasn’t a question. It was an offering. Quiet, and careful, and delivered without expectation of anything in return — the offering of someone who had been alone for two centuries and still, somewhere under all of it, remembered what it was to be useful.

Rai leaned back against the nearest tree and settled in to listen.

—

Territory, Haruto explained, was the fundamental architecture of demon survival.

Every demon claimed a space. A forest, a mountain pass, a stretch of road, a village, a district of a city. Yours was yours. Others stayed out, or they paid for the intrusion with whatever they had left to lose. The borders weren’t marked on any map. They were marked in blood and confrontation and the accumulated weight of ‘I was here first and I have defended this longer than you have been alive’.

Upper Moons were the exception. Upper Moons went where they pleased. Everything else moved for them, or didn’t move and learned why that was a mistake.

“And you?” Rai asked. “This forest is your territory?”

“Has been,” Haruto said quietly, “for a long time.”

Which meant Rai was sitting in his territory. Which, technically, meant tonight had started on shaky ground from the very beginning and had only gotten shakier when—

He noticed it.

The change in Haruto’s posture was subtle. A slight shift in weight. A quality of stillness that was different from the stillness of exhaustion — more focused, more ‘directed’. The eyes that had been quietly conversational a moment ago had shifted register.

Rai felt it through the SEN, the way you felt a drop in air pressure before a storm. Something gathering. Something calculating.

Haruto moved.

The attack was faster than the first ones — the hunger had been slightly addressed by the conversation, apparently, or maybe he’d just had time to compose himself, but either way this was a more deliberate movement, a targeting rather than a lunge, a hand going for Rai’s wrist with the grip of someone who had spent two centuries developing their strength.

Rai was already three metres to the left.

He felt the displaced air of Haruto’s hand closing on nothing and watched the older demon’s face complete a full emotional arc in about a second and a half — surprise, recalculation, and then something that landed in a territory somewhere between desperate and fascinated.

“You’re fast,” Haruto said.

“Yes,” Rai said, from three metres to the left.

“How fast?”

“Fast enough that this is going to be very boring for you if you keep trying.”

Haruto looked at him with that hungry, calculating light in his eyes, and what happened to his expression next was something Rai recognised with a cold settling in his chest — the look of someone who had found a solution to a problem they had been living inside of for a very long time. The look of someone who had just done math that came out in their favour.

“Demon blood,” Haruto said quietly. “If it works — if it sustains like human blood — I would never need to hunt again. I could keep you. You’d regenerate. Infinite supply.”

There was no cruelty in his voice when he said it. No malice. That was almost the worst part. He said it with the flat practicality of a starving man doing arithmetic. This was not evil. This was just a person who had run out of better options several decades ago.

“It’s a reasonable idea,” Rai said honestly. “It’s not going to work out the way you’re picturing.”

Haruto moved.

What followed was not a fight in any sense that Rai had ever imagined himself participating in. It was not his fight. He had no technique, no form, no training, no understanding of how to actually hurt another person with his body. What he had was the ability to ‘not be where the attack was’, and he used it with a thoroughness that surprised even him — SEN feeding him the shape of each strike before it committed, AGI carrying him clear of it, the two stats working in a loop that turned every attack into a question he’d already answered.

He couldn’t hit back. Every time he tried, he’d throw a punch or a shove with no idea what he was doing, the mechanics all wrong, the timing worse, and Haruto’s VIT absorbed it the way a cliff absorbed waves — present, impassive, unimpressed. The difference in strength was real. If Haruto got a grip on him, it was over.

So he just didn’t let Haruto get a grip on him.

Dodge. Redirect. Step. Haruto’s hand hit a tree trunk behind where Rai had been. Rai shoved him sideways. Haruto recovered. He came again. Rai wasn’t there.

‘I can’t keep this up forever’, he thought, watching Haruto circle. ‘He’s level sixteen. He’ll adapt. He’ll change his pattern. And the second he changes his pattern in a way I haven’t accounted for—’

He needed to end it.

He looked at Haruto — actually looked, with all twenty-one points of SEN applying themselves to the problem — and found what he needed. Haruto was exhausted. Long starvation had left their mark. He was slower than his level suggested. His regeneration would be slow too, for the same reason.

‘Slow regeneration’, Rai thought. ‘And one of my abilities is Biological Absorption.’

He let Haruto get close.

Not close enough to be grabbed — he maintained that margin with mechanical precision. But close enough to bait the next lunge, and when it came, he stepped inside it instead of away from it, and he caught the back of Haruto’s head with his forearm, and he used every point of the AGI he’d spent to accelerate Haruto’s own momentum — forward, down, face-first into the root-buckled ground.

The impact was significant.

Haruto didn’t get up immediately.

Rai moved.

He didn’t fully understand how ‘Biological Absorption’ worked. He had a theory, constructed from the name and the context and the way the ability had listed itself between ‘Regeneration’ and ‘Flesh Manipulation’, a sequence that implied something about the relationship between consuming, integrating, and reshaping. He reached toward Haruto with it the way he’d reached toward the stat panel earlier — a mental gesture, an intention directed at something that was supposed to respond.

It responded.

The sensation was unlike anything he had words for. Something in his hands, in his skin, began to ‘take’. Not painfully. Not violently. With a slow, inexorable patience, like deep water absorbing heat — the boundary between himself and the demon beneath him beginning to blur, Haruto’s biology beginning to cross into his own, the absorption starting at the contact point and working inward.

Haruto jerked. Made a sound that Rai didn’t want to think about too carefully.

And then the panel appeared.

[Biological Absorption in progress.]
[Target: Haruto | Level 16]
[Absorption complete. Digestion initiated.]
[Estimated digestion time: 45-60 days.]
[EXP will accumulate continuously throughout digestion period.]

Rai sat back on the forest floor.

The forest was quiet around him. It had been quiet through the whole fight, he realised — not the quiet of something afraid, but the quiet of something that had seen this kind of thing before and had nothing new to say about it. Old forest. Patient forest. It had watched stranger things than this for longer than Haruto had been a demon.

Rai looked at where Haruto had been.

He sat with it for a while.

Then he looked up at the sky through the canopy, at the clean dark with its scattered light, at the world he was living in now, and he thought about a farmer who had wanted to feed his siblings, and about all the things that wanting had cost him, and about the two hundred years of a forest learning to hide from someone who had never wanted to hunt it.

He didn’t feel triumphant.

He felt tired.

Which was interesting, given that demons apparently couldn’t sleep.