My Sister-Obsessed Brother Is a Walking Nuclear Bomb
'That crazy bastard... What if he found out that a bearded, twenty-something dude like me is inside his precious little sister's body...?'
I was slumped on the floor, gasping for air in the wake of the queen's whirlwind departure, when I heard it. Thud. Thud. Thud. Something enormous was approaching from the far end of the corridor. The footsteps were so heavy and rough that the marble floor vibrated faintly beneath me. It was the kind of savage stride that treated royal etiquette like something to be fed to the dogs, and it was heading straight for my room.
My mercenary instincts screamed in alarm. That wasn't the sound of an ordinary person. Those were the steps of a warrior whose muscles had been forged to the absolute limit, bones honed to a razor's edge for swinging a blade. And not just any warrior—this was a superhuman powerhouse that a lowly knight like my old self wouldn't even dare to look at directly.
Bang!
The massive iron door flew open with enough force to nearly shatter, before the maid could even reach for the handle.
"My beautiful little sister! Your big brother has arrived!"
The one who barged into the room was a giant who looked like he could chew up a bear and spit out the bones. The kingdom's first in line to the throne. And the biological older brother of this body—Crown Prince Leonhardt.
His appearance was far closer to a barbarian warrior from the front lines than a prince. Beneath a thin tunic soaked with sweat, rock-hard pectorals and biceps that looked ready to burst writhed with power. He had clearly just come from swinging a sword in the training grounds. A thick wave of manly sweat and the acrid scent of iron filings rolled off his heated body.
"Y-Your Highness the Crown Prince. To enter Her Highness the Princess's bedchamber without even cooling down from your sweat..."
Margareta tried to block him in a panic, but Leonhardt simply shoved her aside lightly and strode straight toward me.
"Nonsense! What's all this fuss about wanting to see my one and only sister's face?"
His gaze landed on me, collapsed on the floor. For a split second, his beast-like eyes widened, then immediately melted into the look of an anxious puppy. Without warning, he grabbed my waist with both hands and hoisted me clean off the ground.
It was as effortless as picking up a feather. To me, it was nothing short of a disaster.
"Urk...!"
My breath caught in my throat. The moment those massive, pot-lid-sized hands clamped around my slender waist, the corset's boning crushed mercilessly into my ribs. It felt like my ribcage was about to shatter. This frail female body had no chance of resisting the insane strength of the crown prince.
"B-Bro... ugh!"
When I let out a pained groan, he yanked me into a crushing hug against his broad chest. My soft breasts were smashed flat against his rock-hard pectorals. The pressure was on an entirely different level from when the queen had embraced me. I was completely trapped in the arms of a muscular man. His scorching body heat and the wild pounding of his heart transmitted straight through the thin silk of my dress.
"Aah, my dear sister... So it's true what Father and that old head magician said—they finally took proper measures. Look at that healthy flush on your once-pale cheeks! Your big brother is so happy he's about to cry!"
Leonhardt rubbed his stubbly chin against my cheek, shouting with pure joy. That's not a healthy flush, you insane muscle pig. My face is red because I'm dying of humiliation and this goddamn corset is squeezing the blood into my head. I screamed internally, but I couldn't let a word of it slip out.
And that wasn't even the worst part. Every time he hugged me tight and rocked me back and forth, a horrific crisis struck my lower body. Rustle. Squish. The thick diaper stuffed between my legs collided with his thigh, producing an obscenely loud friction sound. My bladder, already pushed to the limit from holding it in while drinking black tea, was reaching its breaking point. Every jolt to my tightly cinched lower belly sent electric tingles shooting through the tip of my urethra.
'Fuck, I'm gonna piss... I'm seriously gonna piss myself! Let go! Let me go, damn it!'
I trembled in terror. I twisted my legs desperately, clenching every muscle in my inner thighs until veins bulged, fighting with everything I had not to lose control of my bladder. Physiological tears welled up in the corners of my eyes.
But this oblivious, muscle-brained sister-complex brother completely misinterpreted my shaking.
"Ooh, my poor little thing. Are you so moved to be back in your brother's arms after so long? You're even tearing up. Don't worry. Now that you won't collapse anymore, I'll stay by your side and protect you for the rest of your life."
He stroked my hair. His calloused, sword-roughened palm ruffled through my soft silver locks. Normally I would've punched him for being gross, but right now I didn't have the strength to lift a single finger—I was too busy defending my bladder.
That was when Leonhardt's gaze shifted toward someone standing in the corner. The gentle smile vanished from his face in an instant, replaced by a spine-chilling killing intent that flooded the room.
It was my original body. The hulking mercenary currently occupied by the real princess's soul.
"So you're the escort knight Father newly assigned to her?"
The crown prince's voice had grown so cold and heavy it was hard to believe it came from the same person. The aura of a top-tier powerhouse—one foot already past the threshold of Sword Master—weighed down the entire room like lead. The murderous pressure was so overwhelming it was difficult even to breathe.
"Uh... Y-Yes! That's correct!"
The fake princess inside my burly body answered energetically while carefully reading the room.
Still holding me with one arm, Leonhardt strode right up to my original body. Even my old 190-centimeter frame looked half a hand shorter in front of this monstrous crown prince.
"Listen well, you worm."
His eyes were filled with pure disgust and wariness. He glared at my original body with a look that suggested he might grab it by the collar at any moment.
"My one and only little sister is more fragile and pure than a glass sculpture. If your filthy gaze lingers on her body for even one second, I'll gouge out your eyeballs."
"Hiiik...!"
"And if even a single scratch appears on my sister's body... No—if you dare lay so much as a fingertip on her under the excuse of guarding her, that very day I will tear your limbs apart and hang them from the castle walls. Do you understand?"
It was a brutal warning. He wasn't just trying to scare the guy. He meant every word.
I shivered like a leaf in his arms. Not because my original body was being threatened—but because that insane sister-complex's warning was essentially a death sentence aimed straight at me.
'You crazy fuck... If that bastard ever found out that a freshly twenty-year-old bearded man is inside his little sister's body...?'
Just imagining it made my legs go weak. It wouldn't end with having my limbs torn off. He'd probably grind my bones to powder and burn my soul to ash. The most dangerous bomb in this kingdom wasn't the king—it was this deranged, muscle-headed, sister-obsessed crown prince.
"A-Answer him, knight! D-Does your older brother have to ask twice?!"
I shouted desperately without thinking. It was a desperate, artificial voice squeezed out for the sake of survival—made as sweet and delicate as possible. I even forced myself to say the disgusting word "older brother" while shooting the fake princess a frantic look. Hurry up and answer. Otherwise we're both really dead.
Startled by my sharp tone, the fake princess nodded her head frantically.
"I will keep it in mind! I will protect Her Highness with my life!"
"Hmph. At least your mouth works. I'll confirm your skills with my own hands tomorrow in the training grounds."
Leonhardt let out a cold snort, then turned back toward me. The killing intent vanished in a flash, replaced once again by the honey-dripping face of a doting idiot brother. The man was a walking split personality.
"There, there, my lovely Celestia. Did you get scared? I'm sorry your big brother showed you such a frightening side. I only came to check because I was worried after hearing Father had placed an unworthy knight by your side."
He pulled me into another tight hug. Oh no. This is really bad. I couldn't hold it anymore. The tightly cinched corset pressed into my solar plexus while his massive forearm crushed my lower belly. The dam of my bladder, swollen to its absolute limit, nearly burst.
"B-Big brother... I-I can't breathe... Please put me down..."
I gasped and pushed weakly against his chest. With this frail body's strength, it was no different from trying to push a boulder, but my expression must have looked truly desperate because he flinched and gently set me back on the floor.
"Ah! What was I thinking! What if I damaged this delicate body! I'm sorry, my sister!"
The moment my feet touched the ground, I clamped my thighs together so tightly there wasn't a single gap. Rustle. The thick diaper pressed firmly against my inner thighs. Cold sweat poured down like rain. I was so close to the edge that even the mere fantasy of wetness spreading inside my underwear felt torturous. Every deep breath sent a dribbling sensation from the tip of my urethra that tormented my brain.
"Are you feeling unwell? Your face suddenly went pale."
Leonhardt leaned in with a worried look.
"N-No... I just practiced too hard for the ball... I'm simply a little tired, that's all."
"Oh dear! The academy is right around the corner, but there's no need to push yourself! And if you don't have a dance partner for the ball later, your big brother will gladly be your partner, so don't worry! Wahahaha!"
Fuck, please, anything but that. I screamed internally, blood practically pouring from my heart, but on the outside I could only force a twitching, awkward smile.
"W-Well then, your big brother will return to his sword training. Rest well! Margareta! Serve my sister the finest meal!"
He laughed heartily, planted a loud kiss on the top of my head, and stormed out of the room like a typhoon once again.
Bang!
The door slammed shut violently, followed by the receding sound of those enormous footsteps.
"Haaaaah..."
The moment his presence completely disappeared, I collapsed onto the floor. My legs gave out and as I slumped down, the soft diaper made its presence known once more, but I didn't have the mental energy to care about it anymore. My back was drenched in sweat, making the silk dress cling to my skin. The killing intent that had squeezed my lungs, combined with that even more horrifying onslaught of brotherly affection. What if that oblivious muscle pig had noticed I needed to use the bathroom? Or worse—what if my true identity had been exposed?
The fake princess in my original body stood blankly in the corner, while Margareta pressed a hand to her forehead and let out a deep, exhausted sigh.