Uchiha power in HxH world - Chapter 10

Chapter 10: The Heaven Cursed Seal and the Economics of Madness

The problem with fighting a man who had fifty years of combat experience was that even after the physical damage was instantly healed, the psychological bruising lingered.

I sat cross-legged in the center of my bedroom, surrounded by towering stacks of high-end server racks and glass display cases filled with pristine anime figurines. Normally, just looking at my limited-edition ‘Hunter x Hunter’—well, in this world it was just called ‘Hunter’—merchandise brought me a sense of deep, otaku peace.

Today, it just made me hyper-aware of how fragile I really was.

“Kasuga,” I called out, not opening my eyes.

The heavy steel door didn’t even make a sound this time, but my Perception picked up the subtle shift in the room’s air pressure.

“Yes, Master Milluki?” she asked, her voice an unwavering monotone.

“Cancel my afternoon gaming sessions,” I ordered, my voice carrying the petulant, authoritative whine I had perfected. “And bring me a steady supply of caffeinated sodas. The imported kind. I have a fundamental flaw in my combat algorithm that requires immediate patching, and I don’t want Papa or anyone bothering me.”

“Understood,” Kasuga replied smoothly. “Shall I inform the kitchens to withhold your solid meals as well?”

“Are you insane?” I snapped, my eyes snapping open to glare at her. “I need the calories! Bring the A-grade meat on a rolling cart. I’m going to be doing some intense theoretical reading.”

Kasuga bowed and melted back into the hallway.

Once I was alone, I let out a long, heavy sigh. I rubbed my right forearm. It was perfectly intact, the bone completely seamless, but my brain kept phantom-flashing back to the sickening ‘snap’ of Hideo’s heel crushing it against the stone courtyard.

My speed was phenomenal. My Agility was sitting at a monstrous 100. With the Body Flicker technique, I was moving faster than a human eye could track. But speed without mass, without kinetic weight, was utterly useless against a heavily fortified Nen user. Hideo had simply cloaked himself in ‘Ken’ and let me shatter my own knuckles against his aura.

I needed stopping power. I needed brute strength that could bypass a dense aura defense.

“System,” I muttered. “Open the Library.”

The massive, sprawling catalog of jutsu materialized in front of me, glowing softly in the dim light of the monitors. I aggressively filtered the list, bypassing the elemental ninjutsu and the genjutsu, diving straight into the Taijutsu and Chakra Control categories.

I was looking for a very specific technique. The ultimate equalizer for physical combat.

[Chakra Enhanced Strength]
‘Description: An advanced application of chakra control. By precisely gathering a dense concentration of chakra into the hands or feet, and releasing it at the exact moment of impact, the user can generate devastating, localized kinetic force capable of shattering bedrock.’

I smiled. This was it. The signature move of the Fifth Hokage, Tsunade, and her disciple, Sakura Haruno. It didn’t matter if you were physically weak; if you had perfect control, you could punch a hole through a mountain.

I tapped the scroll to purchase it, the system instantly injecting the theoretical knowledge into my brain.

The mechanics were incredibly complex. It wasn’t just about pushing energy into your fist; it was about holding it in a hyper-compressed state and releasing it in a microscopic fraction of a second. If you released it too early, the energy dissipated harmlessly. If you released it too late, the recoil would shatter your own arm.

I stood up, focusing on my newly acquired knowledge. I pulled the chakra from my core, trying to funnel it down my arm and compress it into my right fist.

Instantly, a heavy, sluggish resistance pushed back against my will. It felt like trying to force wet cement through a garden hose. The chakra fought me, stubbornly refusing to compress, leaking out of my skin in a useless, glowing blue mist.

I gritted my teeth, straining until veins popped on my forehead. Finally, a small, unstable sphere of chakra formed around my knuckles.

I stepped forward and punched the reinforced steel of my computer desk.

‘Clang.’

The desk rattled. A small, almost invisible dent appeared in the metal.

I stared at my fist, panting heavily. That was it? That was the devastating power that was supposed to shatter mountains?

A system prompt blinked mockingly in the corner of my eye.

[Chakra Enhanced Strength Lv1 (0/500)]
[Notice: Technique relies heavily on Yang (Physical/Vitality) attribute affinity. Host possesses Yang Lv2.]
[EXP Penalty Applied: Due to low affinity, Host will accrue EXP for this technique at an 8x slower rate compared to Yin-based abilities.]

My jaw dropped. “Eight times slower?”

I fell back into my chair, burying my face in my hands. The realization hit me like a bucket of ice water.

This was the first time I had truly confronted the fundamental flaw of the Uchiha bloodline. In the anime, they were portrayed as the ultimate, overpowered Mary Sues of the ninja world. They had the Sharingan, they could copy anything, they looked incredibly cool while brooding.

But they weren’t perfect. They had a glaring, genetic weakness: their raw brute power.

The Uchiha were masters of Yin—the spiritual, the imagination, the intricate manipulation of shape and illusion. But Yang—the physical, the vitality, the raw, unadulterated life force—belonged to their eternal rivals, the Senju clan. It was the reason Hashirama Senju could heal without weaving hand seals and punch mountains into dust, while Madara Uchiha had to rely on giant chakra mechs to do his heavy lifting.

My Yin affinity was Level 5. My Yang was a pitiful Level 2. I could theoretically learn Chakra Enhanced Strength, but grinding it to a usable level would take decades of agonizing, low-yield effort. It would always be weak compared to my other skills.

“I can’t brute force this,” I muttered, spinning my chair around to face the ceiling. “I need a workaround. If I can’t generate the physical power internally, I need to draw it from an external source.”

My otaku brain instantly began cataloging the lore.

What was the ultimate power-up in the ‘Naruto’ universe that boosted all physical attributes and ninjutsu power simultaneously?

‘Sage Mode.’

The mastery of Senjutsu. By perfectly balancing internal physical and spiritual chakra with the external natural energy of the world, a user could enter Sage Mode, granting them borderline god-like strength, speed, and sensory capabilities. It was the perfect solution.

I hurriedly opened the Library, typing ‘Sage Mode’ into the search bar.

A single, glowing gold scroll appeared.

[Sage Mode (Toad/Snake/Slug)]
[Status: Locked.]
[Requirement: Minimum Kage-level Chakra capacity (2,000+ CP). Intense, localized Nature Energy environment required for initial synchronization.]

I stared at the 2,000 CP requirement. I currently had 745. Even with the exponential growth of my level-ups, hitting two thousand would take months, if not a year, of non-stop grinding.

“Damn it,” I hissed. “There has to be another way. No pure-blooded Uchiha ever naturally learned Sage Mode in the original timeline. Madara only got it because he literally grafted Hashirama’s flesh onto his own chest. And Sasuke…”

My eyes widened. The thought struck me like a bolt of lightning.

Sasuke Uchiha didn’t learn traditional Sage Mode. He used a bastardized, synthetic version of it for the entire first half of the series.

The Cursed Seal of Heaven.

Given to him by Orochimaru, the seal was created by isolating the genetic mutations of a man named Jugo—a clan whose bodies naturally, passively absorbed nature energy without needing to remain perfectly still. The seal forcibly flooded the user’s body with Senjutsu chakra, granting them massive physical strength, speed, and a terrifying aura.

It was exactly what I needed. A hidden ace card. A trump card I could activate when I was backed into a corner and needed to turn a heavily armored Nen user into paste.

My fingers flew across the holographic keyboard, typing ‘Cursed Seal’ into the search bar.

A dark, ominously purple scroll materialized on the screen.

[Heaven Cursed Seal]
‘Description: A synthetic, highly aggressive Senjutsu conduit. Forcibly draws Natural Energy from the environment, blending it with the Host’s chakra to artificially induce a localized Sage Transformation. Massively increases STR, AGI, VIT, and overall Jutsu potency.’

I read the description, my heart hammering in my chest. This was it. But I wasn’t stupid. Orochimaru’s cursed seals were notorious for housing fragments of his soul, effectively turning the user into a biological hard drive for his eventual resurrection.

I scanned the fine print at the bottom of the scroll with my Sharingan, looking for the catch.

‘System Note: Construct is synthesized purely from baseline genetic templates (Jugo origin). No foreign spiritual entities or soul-fragments are attached to this skill construct.’

“Thank God for the System,” I breathed a sigh of relief. No snake pedophiles hiding in my neck.

But there was another warning. A glaring, red text box that pulsed urgently.

‘WARNING: The Heaven Cursed Seal is derived from a highly unstable genetic mutation. The seal passively and continuously absorbs Natural Energy from the environment. Due to the volatile nature of unfiltered Senjutsu, excessive accumulation will result in severe psychological degradation.’

‘If stored Natural Energy exceeds 50% capacity, the Host will begin to experience extreme aggression, paranoia, and violent compulsions.’

‘If stored Natural Energy reaches 100% capacity, the Host will undergo full biological hijacking, devolving into a mindless, feral beast driven solely by the instinct to slaughter.’

I froze, reading the warning three times over.

It was a ticking time bomb. The seal didn’t just turn on when I wanted it to; it was a permanent, gaping hole in my spiritual defenses that constantly pulled volatile nature energy into my body. If I didn’t actively manage it, I would literally lose my mind and go on a murderous rampage.

And considering I lived in a house with Zeno, Silva, and Illumi Zoldyck, going on a feral, mindless rampage was a guaranteed death sentence. They would put me down like a rabid dog before I made it out of the hallway.

“Is the power worth the risk?” I whispered to myself.

I thought about Hideo. I thought about the Phantom Troupe, who would eventually arrive in Yorknew City. I thought about the Chimera Ants. The ‘Hunter x Hunter’ world was entirely too dangerous for me to play it safe. If I wanted to survive the endgame, I needed power, and I needed it now.

I reached out and pressed the glowing ‘YES’ button.

The system interface vanished. For a split second, nothing happened.

Then, an agonizing, white-hot spike of pure, unadulterated agony drove itself directly into the left side of my collarbone.

“GAAAAAH!”

I fell out of my chair, crashing onto the carpet, my hands frantically clawing at my own shoulder. It didn’t feel like the electrical torture of ‘Heavens Step’. This felt incredibly localized, like someone was pressing a branding iron made of liquid magma directly against my skin, slowly twisting it into the muscle.

I tore the collar of my tracksuit open.

There, burning themselves into my pale skin, were three black tomoe. They rotated in a tight circle, leaving a trail of blistering, bruised flesh in their wake, before finally locking into place. The iconic pattern of the Heaven Cursed Seal.

The pain slowly subsided, replaced by a strange, heavy, throbbing sensation. It felt like I had a second heart beating right under my collarbone, pulsing to a rhythm entirely disconnected from my own.

I lay on the floor, gasping for breath, as the system panel re-materialized in my vision.

‘Ding!’
[Skill Acquired: Cursed Sage Seal Lv1 (0%)]
[Integration complete. Passive Environmental Absorption Initiated.]
[Notice: Host has acquired the Unrestricted Version of the seal. No secondary suppression barriers detected.]

I stared at the last line. ‘Unrestricted version.’

In the anime, Kakashi Hatake had placed an intricate, highly complex sealing formula around Sasuke’s cursed mark to suppress it, keeping the passive absorption at bay unless Sasuke actively forced it open.

I didn’t have Kakashi. I didn’t know sealing jutsu. The system had given me the raw, unfiltered, wide-open version of the seal.

A new metric appeared on my master status panel.

—

Name: Milluki Zoldyck

Bloodline: Uchiha Lv3 (75%)

Level: 49 (629/1275)

Affinity: Fire Lv3, Yin Lv5, Yang Lv2, Lightning Lv4

…

Health: 570/570 [Recovers 0.8% per minute]

Chakra: 745/745 [Recovers 0.2% per minute]

Fatigue: 0%

N-Energy: 0.1%

…

STR: 34

AGI: 100

VIT: 80

INT: 20

PER: 24

…

Skill: Sharingan Lv3, Chakra Control Lv4(82%), Transformation Lv1(12%), Clones Lv1(83%), Body Flicker Lv2(54%)

Ability: Poison Resistance Lv4(0%), Pain Tolerance Lv4(1%), Cursed Sage Seal Lv1(0%)

…

[Library]

—

I stared at the N-Energy: 0.1% metric. As I watched, the number flickered, holding steady.

“System,” I asked, my voice trembling slightly. “What is the exact rate of passive absorption?”

A prompt appeared instantly.

[Current Environmental Absorption Rate: 0.1% per minute.]

My 20 Intelligence went to work, crunching the numbers with cold, terrifying precision.

0.1% per minute.

That meant 6% every hour.

To reach the 50% threshold—the point where my mind would start degrading into violent paranoia and aggression—it would take exactly eight hours and twenty minutes.

To reach 100%, total feral hijacking, it would take roughly sixteen hours.

I sat up, the blood draining completely from my face.

“Sixteen hours,” I whispered, panic finally breaking through my gamer detachment. “I have sixteen hours before I turn into a monster.”

If I went to sleep for a standard eight hours, I would wake up right on the absolute edge of losing my mind, practically rabid. I was a literal, biological time bomb living in a house full of the world’s deadliest assassins.

I scrambled to my feet, pacing the floor of my room frantically.

“Okay, calm down. Calm down,” I muttered, slapping my own cheeks to focus. “It’s an energy pool. If it fills up, I just need to empty it. How do I decrease the stored energy?”

I pulled up the Help menu for the Cursed Sage Seal.

‘To decrease the volume of stored Natural Energy, the Host must actively expend it by substituting Senjutsu chakra in place of standard chakra during the execution of jutsu.’

“Right,” I nodded, feeling a small surge of relief. “I just need to use jutsu. I need to burn it off. It’s like venting steam from an engine.”

I needed to test the vent immediately. I was already at 0.5%.

The most consistent, passive drain I had in my arsenal was the Sharingan. At the Third Tomoe, it consumed 3 CP per minute to maintain. If I powered it with the newly acquired Senjutsu chakra from the seal, I could just leave my Sharingan on for a few hours a day to bleed off the excess nature energy.

“Activate,” I commanded.

I felt the heavy, thrumming energy from the seal on my collarbone route itself upward, mixing violently with my own chakra before flooding into my optic nerves.

My eyes burned, shifting into the blood-red hue of the Sharingan. But this time, it felt different. The world didn’t just slow down; it snapped into a terrifyingly sharp, hyper-focused clarity. I could see the individual dust motes floating in the air. I could sense the faint, latent aura lingering on the walls of my room. The Senjutsu chakra was amplifying the visual prowess of the dojutsu exponentially.

I checked the system panel to verify the drain.

Instead of a drain, a new, horrifying notification popped up.

[Senjutsu Chakra Integration Successful.]
[Notice: Natural Energy drastically increases the potency and efficiency of Yin-based constructs.]
[Sharingan consumption rate has been halved. New cost: 1.5 CP per minute.]

I stared at the screen, my red eyes wide with disbelief.

“You have got to be kidding me,” I said, my voice barely a whisper.

The system was too good. The Senjutsu chakra didn’t just power the jutsu; it made the jutsu fundamentally more efficient. It had cut the maintenance cost of my Sharingan in half.

At a drain of 1.5 CP per minute, the amount of N-Energy I was actually expending was minuscule. The passive absorption rate of 0.1% per minute from the environment was vastly outpacing my ability to burn it off through the Sharingan.

I deactivated the red eyes, dropping back onto my bed. The throbbing in my collarbone seemed to mock me.

My “venting” strategy was a complete failure. I had successfully acquired the ultimate physical power-up, but in doing so, I had cursed myself to an endless, daily struggle for my own sanity.

If I couldn’t burn the energy off slowly, I had to burn it off explosively.

“I need a new jutsu,” I realized, scrolling frantically through the Library once more. “I need something massive. Something wildly inefficient. I need a jutsu that consumes an ungodly amount of chakra in a single cast, just so I can use it as a dump for this nature energy before I go to sleep every night.”

I needed a nuke. And I needed to learn it before the eight-hour mark hit, or the Zoldyck family was going to have a very feral, very dead Milluki on their hands.