In the Academy as Sukuna

"Patience is not just a virtue; it's a weapon. The more you wait, the stronger you become."

(POV: Ryomen Sukuna)

I flicked my wrist, sending an invisible slash at an unsuspecting monster, a goblin, which immediately got split into two, not having time to react.

Its blood pooled on the floor, its eyes slowly losing color and going lifeless, but I was already far ahead.

Sukuna has been running around, killing monsters for the past few hours… I don't know, I lost track of time a while ago.

Sukuna, as a player of the game, knows the mechanics of dungeons, and hence has formulated a technique to gain Cursed Energy Proficiency in the most efficient way using his huge brain.

I paused my narration as I almost hit a large bull standing on two legs at my speed. But I moved to the side, avoiding It narrowly before slashing it with my knife, splitting it into three with ease. Some of its blood splattered on me, making me wince.

'With my knife' you ask?

Well, dear friend, this is the knife I found in the weapon selection on the first day, something which I've never used… or, never been able to use.

You see, when I first got the knife, I was trying to practice with it, when I suddenly felt some of my cursed energy disappear, and the knife disappeared from my hands.

The System screen popped up, saying [Inventory (1/4)]

'I have an inventory?' I had thought, shocked.

However, something I realized quickly was… I didn't know how to take it back out.

However, while I was grinding, the knife suddenly popped up in my hand, I was unsure why, but it wasn't the time to think of it.

Continuing my grind, I ran ahead, deciding to continue the narration… I had nothing better to quench my boredom.

Monsters in dungeons increase in strength as one goes closer to the boss room, and these monsters give more EXP.

What is EXP, you ask?

EXP allows me to level up, but I didn't think of it at all since the System told me that I can't level up.

However, I can level up, and each level increases only one thing, Cursed Energy Proficiency.

Sukuna has figured out that the EXP required to level up increases exponentially with each level, and each level up gives 1% Cursed Energy Proficiency.

He has also, using this very thing, unlocked something quite formidable.

Why am I talking in third-person? I don't know. Also, hey! It's been a while.

Monsters use the mana from the dungeon core to be spawned, once a room is cleared out, the monsters start respawning.

The respawn mechanic only happens in certain rooms, though.

I've chosen two rooms, I kill all the monsters in one room, then move to the other, killing all the monsters there.

Nina was quite… confused about why I was doing this, to say the least.

Even though she, in my eyes, is a nice person who I feel closer to than most, I wouldn't, in a sextillion years, tell her about the System.

She was in another room, either resting or training mildly.

I need her to be a good asset for now, and not to be scared of me at all. After all, a good team is formed only by equals.

That is why, while training Reverse Cursed Technique, I made sure to be in a completely different room from her, or at least out of her sight.

I slashed the last monster in the room, running out of the doorway into a tunnel, which led to another room, which was quite small compared to the rest.

Blood pooled on the floor, the metallic, pungent smell wafting in the air, assaulting my nose.

This blood was, obviously, mine.

I've been meticulously training Reverse Cursed Techniques whenever I get a break. And I have to say, I'm just so good at it.

A smirk formed on my face as I opened my mouth. "Doggo," I called, my voice echoing in the confines of the dark room, ripples forming in the pool of blood as a small dog walked over it.

The dog was tiny, almost like a puppy, but in its eyes was an insatiable hunger. It lunged towards me, its teeth digging into the flesh of my arm.

I simply let it, sitting down, my back on the wall as I stared at the ceiling, focusing on healing my injuries.

Doggo was an E-Rank monster, one which I picked up at the start of the dungeon run.

I winced in pain as he bit a chunk of flesh off my arm, exposing my muscles and bone.

It really hurt… a pain that would make me pass out, but I simply healed it back, slightly groaning at the burning sensation as the whole part regenerated.

At first, it hurt… it hurt too much. I screamed, I thrashed around.

A smirk formed on my face as I remembered the time a few hours ago, how I almost killed Doggo in panic.

However, it was almost like I was used to the pain now… I'm not even sure if a person should get used to pain this quickly. Or maybe, I was just special.

My body slightly shivered as my gaze met the hungry eyes of Doggo again. He shot towards, me, his sharp canines digging into my thighs as he pulled another chunk of flesh away, chewing it violently.

"You're hungry, huh?" I muttered, focusing on healing my wounds, grimacing again.

At these moments, I can't help but wonder… what does [Unshakeable Heart] even do?

It's a skill I've had for a while, and it has almost never activated.

I let Doggo bite me the first time, confident that [Unshakeable Heart] would cancel out, or at least decrease the pain, but what it resulted in was me screaming at the top of my lungs.

I sighed, rubbing my forehead with my fingers, my gaze going to Doggo, who was chewing my flesh savagely.

"You know Doggo," I muttered. He glanced at me for a second before going back to eat. "There are two types of NTR in this world."

Doggo stopped its chewing for a second, as if it froze, but soon continued in a seemingly more violent manner.

I continued, not paying him any mind, even though I was supposedly talking to him. "Bad NTR, a dude taking away wives, breaking homes."

I paused, leaving an uncanny silence in the room. The only audible sounds were that of Doggo chewing my thigh and my ragged breathing.

"Good NTR," I continued, my voice reverberating in the small room. "The journey of improvement of an NTR'd guy, satisfying to watch."

I raised an eyebrow, realizing something.

The hell was I doing? Talking to a dog trying to eat me? Teaching him about NTR?

Doggo finished his meal, turning to me again as I sighed, knowing what was about to happen.

He bit a chunk of flesh out of my forearm, his choice this time around. It hurt more because there were more muscles there.

I winced as I stood up, my leg bending backwards as Doggo's gaze met mine. I kicked him, sending him flying to the other side of the room.

He whimpered, landing on the ground with a thud, the flesh still in his mouth.

"See ya later," I said, waving my hand, as I shot out of the room before he could attack, continuing my grind.

.

(About an Hour Later)

I had continued killing monsters without end, both the dungeon's walls and the knife were covered in blood, as if it were a huge painting. I sensed four extremely familiar presences coming towards me.

My steps halted, my gaze darting to the room where Nina was sitting.

I could see her eyes lighting up as she saw who came through. I smirked, my footsteps slow as I walked towards them.

"Guess who finally decided to come," I said quite loudly, my voice echoing in the tunnels as I walked to a position in front of them.

I could see their eyes widening in sync, their gazes roaming over me and my bloodied clothes.

Anny glanced at Nina, who just shook her head with a hesitant smile.

Anny's gaze came back to me, her eyes glinting with curiosity, but she decided to not ask anything for now.

A silence followed, one that felt almost too loud,

"Should we rest for a little while?" Nina asked from the side, her lips curled up in a nervous smile as she tried to diffuse the awkward yet tense atmosphere.

There was no response for a few seconds, before Alexia broke out of her trance, turning to Nina with a smile. "I don't think so… we rested just before coming here."

Johan and Anny nodded, but Ryogaku seemed to be lost, his eyes fixed on my bloodied t-shirt. I could see his hand trembling, his face was twitching as if he was trying hard to not wince.

"Is that so?" I said, turning to the side, getting Ryogaku back to his senses. "We'll be going right now, then."

I pointed at a room, one which somehow seemed darker than any other they had encountered.

There was no need for an explanation, their fearful and determined expressions told me that they understood. This was the boss room.

I waited for a few seconds, and nobody voiced any objections. I simply nodded, turning around and walking towards the tunnel.

Their nervous footsteps followed mine. I could feel Ryogaku's gaze boring into my back… I wonder why he's like this today.

The atmosphere got more oppressive, Nina being affected by it the most. Her hands were trembling, she fumbled her steps, struggling to walk straight.

I turned back to her, offering her a comforting smile. That seemed to work a little, her eyes glinted with determination as she tried her best to stay calm, returning me a nervous smile in response.

My eyes narrowed as I turned back… she will be a burden.

We finally reached the end of the tunnel, and what we saw at the end was something that seemed to be straight out of a game.

Because it was.

There was a huge gate made of rusted iron, possibly the only structure I had seen in the dungeon made of anything but rock.

It was the only protection between us and what lay inside. It had ornate carvings that seemed to glow a slight red as we walked towards it, a dense, dreadful aura emanating from it.

Two colossal statues, depicting courageous and forgotten warriors, their expressions intimidating, flanked either side of the rusted chunk of metal.

My eyes slightly widened, my breathing fastening. I felt something inside me… something that reminded me of the dangers of a B-Rank dungeon.

My hand gripped the knife's handle tightly, my heart beating faster the longer I gazed at the threatening presence of the gate.

As we stood in front of the gate, the air was thick with anticipation as the group readied their weapons, their eyes burning with a fire of unyielding determination.

My heart was pacing, each beat reminding me of what we were about to face. I took a deep breath, readying myself for what was to come.

"Alright then, we're going in," I said, my voice trembling ever so slightly as I glanced back at my team, taking in their varied reactions.

Anny, Johan and Ryogaku seemed pretty calm, their expressions showing silent resolve. Alexia and Nina, however, were more affected, their breathing ragged as their eyes burned with a passionate desire to prove themselves, trying to mask their fear.

I placed my hands on the metal frame of the door, the cold pricking my skin. I pushed with sufficient force, the door slowly moving on its hinges which seemed to not have been used for centuries.

The door opened slowly, with a high-pitched creaking sound, revealing...