My Sister's First Experience Belongs to Her Brother
"It feels so good when you suck my nipples, Brother♡" Cordelia cried out as I lavished attention on her breasts. The nipple I had gently bitten down on grew even harder against my tongue.
"Something that feels this amazing… and you’ve only been enjoying it with Aunt and Raibel until now? That’s so unfair, Brother♡" Cordelia’s hands slid slowly up and down my back, stroking from the base of my spine upward. It felt like a mother gently rubbing her baby’s back to prevent it from getting a stomachache after feeding.
"From now on, you can’t have sex with Aunt or Raibel anymore. You can only have sex with your loving little sister, haang♡"
I pulled my mouth away for a moment. A thin, transparent string of saliva connected my tongue to Cordelia’s glistening nipple.
"…Can we talk about Masha and Raibel later?"
"Why? Does it hurt your heart to think about your other beloved women while you’re inside your own sister? I’m family, and they’re just lovers?"
For an instant, Cordelia’s eyes turned ice-cold. The low, chilling tone was the Cordelia I had originally known. Her viper-like response, as if she had prey in her jaws, nearly made my cock—still buried deep inside her tight walls—shrink like a deflated balloon.
But then Cordelia burst into laughter at the sight of my obvious tension. She playfully poked my nipple with her index finger.
"Hngh♡ Just kidding, hehe. If someone stole your cock away, how heartbroken would Aunt Masha and that crybaby maid be? Besides, you whispered that you loved me earlier. I trust your love, Brother."
With that, she transformed back into the sweet, brother-obsessed little sister, clinging to her big brother. She grabbed her own breasts and pushed them firmly against my face, silently begging me to suck on them again.
…It was a joke, right? I didn’t dare ask. I could already imagine her turning cold and asking if I couldn’t even trust my own loving sister.
Having recovered from the shock of losing her virginity to her own brother in an incestuous encounter, Cordelia now seemed to have regained some composure. I obediently sucked on her nipple as she wished. Meanwhile, she had been persistently toying with my own nipples, teasing them without mercy.
Her touch had turned my nipples a vivid red, but it didn’t hurt at all.
"Hehe… Brother’s nipples are so cute♡ Every time I touch them, your cock twitches inside me♡"
Delighted at discovering her brother’s new erogenous zone, Cordelia wore an expression of pure mischief. And whether it was because of my nipples or not, I was rapidly approaching my limit. I could no longer hold back the surging pressure in my urethra.
"I’m going to cum, Cordelia. I’ll fill you up again."
"Haaang♡ Yes, please. I’ll take all of you, Brother. Pour it all into your little sister’s womb♡"
Cordelia clung tightly to my back. I could feel her sharp, aristocratic fingernails digging into my skin. But before I could register any pain, an even greater wave of pleasure slammed into my lower abdomen. Thick, pure-white semen erupted from my cock.
I had lost count of how many times I had cum. We had been in the same position from the very beginning, and even after each climax I never pulled out—simply waiting for my cock to harden again inside her before continuing. It was only natural that I had already lost track. Considering the sheer volume of semen and my experience so far, I estimated it had to be at least ten, maybe even eleven times.
"So full…" Cordelia murmured. She hadn’t swallowed it orally, but her womb and every inch of her pussy were packed tight with my sticky seed, so it was no wonder her belly felt heavy.
"Does this mean I’m going to have Brother’s baby now?"
Cordelia gently stroked her own stomach with a loving expression. Her innocent question about my intense sex education nearly ignited my lust again, but I held myself back. The academic conference’s opening ceremony was scheduled for this afternoon, and I needed to start preparing to leave. I had also promised to meet Emilia afterward to discuss our future plans.
As her big brother, I answered her curiosity.
"Having sex doesn’t automatically mean you’ll get pregnant."
If it did, Raibel, Masha, Emilia, and Melina’s bellies would have swollen in the exact order they had slept with me.
"R-really…?" Cordelia frowned, clearly disappointed.
I pulled her adorable body into my arms. Our chests, stomachs, and thighs were all slick with sweat, yet none of it felt unpleasant. On the contrary, the wet, slippery sensation of our skin sliding together felt strangely pleasant, like we had been coated in oil.
"Don’t be too impatient. I promise I’ll get you pregnant before we return to the mansion."
"You promise? Then we’ll have to keep using the same room for the next five days, right? Fine, I’ll specially allow it."
"…This is my room, you know?"
Cordelia giggled with pure, playful innocence and tickled my back with her fingertips.
"Hehe, you’re so nitpicky about the little things. Okay, then while I’m here, let’s compromise and call it our honeymoon suite. Happy now?"
Honeymoon suite? Hearing her say something like that instantly made me hard again. Unable to resist, I leaned in to kiss my cute, babbling little sister on the lips.
At that exact moment, the door burst open.
"I told you that you wouldn’t show your face in the auditorium until the opening ceremony ended, and sure enough, here you are—buried inside her, Arwen."
A familiar woman’s voice, cold with restrained fury, rang out alongside the sound of the door slamming open.
"Haah… I can’t believe you’d do something like this in broad daylight. What would you have done if it hadn’t been me who walked in?"
The woman pressing a hand to her forehead, clearly suffering from a headache at the sight of the incestuous siblings in the middle of sex, was none other than Emilia.
* * *
"So… you got swept up in the moment and ended up doing that with your own sister? Completely forgetting the promise you made to me?"
After listening to my explanation, Emilia shook her head in disbelief.
"S-sorry, Emilia. It’s not that I forgot the promise—please believe me."
I felt like cold sweat was about to pour down my forehead, as if I had been caught cheating on my lover. And this wasn’t even ordinary cheating. I had been caught committing the ultimate taboo—incest between family members—something forbidden in ordinary human civilization. There would have been nothing I could say if Emilia had trembled with rage and hurled vicious accusations at me.
But she didn’t.
"Huu… Whatever. I knew it would turn out like this the moment I heard your sister was visiting the academy."
Instead, Emilia simply shrugged as if she had expected it all along, ending her reprimand toward her lover there.
"…Who is that woman?"
Cordelia, who still showed no intention of leaving my embrace despite the sudden appearance of a third party, asked the question. Her gaze was locked onto Emilia. Her eyes openly revealed hostility. Even though this was their first meeting, Cordelia seemed to have instinctively realized it—Emilia was another one of her brother’s women, just like Masha, Raibel, and herself.
Emilia, for her part, refused to back down from Cordelia’s provocation. The shy, socially awkward Emilia I had first met was nowhere to be seen. The two women glared at each other like wild beasts in the wilderness, and the suffocating tension made it hard to breathe.
Still, what could I do? I couldn’t run away. I had to melt this icy atmosphere as best I could.
"Um… This is Emilia Baroque, the professor of the magic potions class I’m taking and…"
"Professor and?"
Cordelia repeated the end of my sentence in that cutesy way people did on the internet to make their lover’s heart flutter. Of course, my heart was fluttering for an entirely different reason.
I swallowed once before answering.
"…My lover."
The moment she heard the word “lover,” Cordelia’s arms wrapped around my back tightened like a vice.
"Lover?"
Cordelia stared at Emilia with a hardened frown. In contrast, a relaxed smile bloomed across Emilia’s face. She seemed quite satisfied with the introduction.
"Nice to meet you, Miss Cordelia. I’ve heard a lot about you from your brother. I’m Arwen’s lo-ver, Emilia."
Emilia deliberately emphasized the two syllables of “lover” as she extended her hand for a handshake.
"…Nice to meet you too, Miss Emilia. I’m Cordelia Reinhardt."
In the end, Cordelia accepted the handshake with a clearly reluctant expression. Once the handshake ended, Emilia looked at the naked siblings who were still locked in a lewd embrace and spoke.
"Shouldn’t you two separate soon? I have something to discuss with Arwen."
Cordelia responded with the smile of a hunter who had just spotted prey.
"Well, Brother and I are quite busy making a baby. If it’s not urgent, could you please leave us alone, Miss Emilia?"
At the same time, Cordelia pressed her soaking wet pussy even more firmly against my crotch with an obscene, wet sound.
"A… baby?"
The sticky, squelching noise made by the siblings caused Emilia’s face to twist as if she had taken a heavy blow.
"You two are brother and sister! How can you talk about having a baby…"
Cordelia lifted her chin defiantly.
"What’s wrong with wanting to personally give birth to an adorable nephew?"
"Ugh, how shameless…"
The room filled with a frigid atmosphere created by the two women’s intense staring contest. At this rate, they looked ready to grab each other by the hair and start fighting. In the end, I had no choice but to intervene between the two jealousy-blinded women.
"Enough! I don’t want to see you two fighting. Both of you, stop it right now."
At my slightly raised voice, both Emilia and Cordelia’s gazes snapped toward me. Realizing how disgraceful they had been acting, they blushed and apologized to each other.
"…I’m sorry. I was rude to Arwen’s family member."
"N-no, I was the one who…"
The brief storm passed, and the room was once again filled with awkward silence. The bizarre scene of two siblings who had just finished having sex sitting obediently in a room with the older brother’s lover was almost too much.
Cordelia was the first to speak.
"What did you mean earlier, Brother? When Miss Emilia said she knew this would happen."
Emilia had spoken as if she had known Cordelia and I would end up in bed together. In truth, she already knew the entire dark history of the Reinhardt family—from the Baroque family and Isabel trying to kill me, to the reason I had trained Masha, all the way to Sophia trying to assassinate me. She even knew that I planned to claim every woman in my family.
Of course, Emilia had been horrified at first. But my passionate persuasion—“I don’t want to be separated from my family! If they hate me, I’ll just make them love my cock instead!”—had eventually led her to promise to cooperate with me. Naturally, I hadn’t persuaded her with such perverted words alone.
At Cordelia’s question, Emilia suddenly turned to me as if she had realized something.
"Don’t tell me Miss Cordelia still doesn’t know?"
I nodded at Emilia.
"That’s right. She doesn’t know yet."
"What don’t I know?"
Cordelia, unable to follow the conversation, looked back and forth between us with a puzzled tilt of her head.
…What should I do?
Could I really tell her the truth? Would Cordelia be able to accept the shocking fact that her own mother had tried to kill her half-brother? Would she take my side?
At that moment, Cordelia, who was sitting beside me, gently placed both of her hands over mine. She looked straight into my eyes.
"…Tell me honestly, Brother. Just like how I honestly confessed my feelings to you."
Her voice was steady, without the slightest tremor, and I could feel the trust in it—the trust that she was ready to accept any truth.
"Alright… I’ll tell you."
In front of Emilia, who watched our exchange with a worried expression, I told Cordelia everything. Every single thing that had happened to me since the moment I possessed this body, without leaving out a single detail.