My Little Sister Is the Best F*p Material

Volume 1 Chapter 01.1: The Day My Sister Became My Fap Material

“If it’s you, Onii-chan, then it’s okay.”

On the bed in the middle of the night, bathed in moonlight. She spread her legs herself, opening up her intimate parts.

Her silver hair fell onto the pillow, and her moist eyes looked at me.

“Biyu… Biyu…!” (T/N: The name of the ‘girl’ from the cultured material he’s watching, not his actual sister.)

My erect penis, already hot and swollen, was further hardened by my right hand’s pumping action.

The four-thousand-hertz sound wave, directly hitting my ear, and the four-million-pixel collection, passing through my organs, stimulated my genitals. This beautiful girl, with her innocent face, was my precious lover, seductively tempting me.

“Onii-chan… ahh… aaah…”

Biyu’s body, still unfamiliar with men, writhed as her vaginal walls were opened. She was an angel, the only one who would never betray me.

“Haa… it feels good… Biyu…”

“Onii-chan, no… don’t be so rough… ahn…!”

“Biyu… I love you… I’m about to…!”

“Onii-chan? Are you in there?”

“Aaah… mi… u…?”

“Onii-chan?”

That voice reached me from behind. From the direction of the room’s door.
I had always believed that my indifferent family would never open it. And yet—

“Nooaaah!? Mi, Miyu?!”

My real sister, different from the one on the display, was standing there. She was standing right next to me, my lower body exposed, looking at me with a puzzled expression on her adorable face.

“No, it’s not like that! I mean, this is not…!!”

I was confused, not knowing whether to hide the screen of me having sex with my sister or my erect penis, excited by the scene.

“But it sure looks like it.”

Miyu, my sister, was looking down at my penis with a serious expression. The glistening head of my penis, swollen with pre-cum, asserted that I was about to ejaculate.

“Sorry for interrupting you. I didn’t notice you were here since you were facing backwads”

“I-Is that so?.”

“What a cute girl, isn’t she?”

“Yeah, she is.”

The desperate moans of Biyu, leaking from the headphones, echoed in the awkward silence that had fallen between us, making me thirsty with discomfort. The audio, unrelated to the text, continued to flow endlessly, even when the auto function was stopped.

“Were you about to come?”

“No, not really… I mean, yes…”

“Hmm. So you were.”

My sister spoke in a calm tone, and again, her eyes fell on my penis.

My sister looked down at my penis again, her large eyes unperturbed by the sight of my engorged male organ. Her lustrous skin, her black hair, and her full, yet toned body—for whom had she prepared all this? When had she learned to be a man’s masturbation material?

Miyu and I weren’t particularly close, and as a hikikomori, I had hardly ever spoken to her. So, I had no idea what kind of youth she was experiencing.

Still, she always had that sullen expression. I had always thought she was innocent because she had never shown any interest in men.

But how could my sister, who had always been so pure, suddenly know about men?

“As an apology, would you like me to help you out?”

“Yeah, um… yeah?”

What did she just say?

“Then excuse me for a bit.”

Miyu walked past me, took the mouse while standing, and bent forward. She unplugged the headphones from the computer, turned to face me, and asked if I was ready. Her white legs, peeking out from her culottes, were incredibly sensual.

Wait, wait. What am I doing, getting aroused by a three-dimensional woman, my own sister, no less?

“Haaun… Onii-chan…! So intense… aah…”

Miyu clicked through the game, making sure all the text was displayed properly before the heroine’s moans of sex with the protagonist ended. Then, she carefully clicked through each page, sending the text.

What?

Is that all she meant by helping me out?

“You don’t need to move your hands?”

Miyu asked, as if it were obvious.

I was overwhelmed with questions, unable to sort them out.

Does my sister not find it strange to watch her real brother masturbate?

“Should I wait a bit more?”

“Yeah… yeah.”

I felt like I was being prompted, so I instinctively placed my right hand on my penis, staring at my sister’s lustrous thighs.

Is this really okay? Right in front of my 2D girlfriend—my little sister—I’m using my real little sister as fap material while I… masturbate.
A double-layered sense of guilt creeps up from around my diaphragm, sending shivers through me.

“Hmm…”

Without realizing it, I was holding my breath.

My right hand began to move slowly, drawing sperm from my testicles.

“Ah… kuh…”

Because of my shallow breathing, my breath mixed with my voice. I paid no attention to Miyu, who was scrolling through the text with care; my eyes were fixed on my sister’s legs.

I had never observed a girl so closely before. I had thought that nothing could surpass the excitement of two-dimensional worlds.

This is bad. My erection hurts more than usual. I want to masturbate even harder.

“Hey… Miyu… Uhm…”

“Hmm? You’re about to come?”

“Yeah… but… I would like to come on…”

I want to cum on her thighs. I don’t want to take a tissue in this atmosphere, and I don’t feel like spilling it on the floor.

“While you’re helping me out…”

If she really wants to apologize.

Just once.

I want to cum on a girl’s thighs.

“Let me cum on Miyu’s thighs…!”

I said it. Even her expression of confusion, the blinking her eyes, was now fuel for my lust.

I had to admit it. I was excited by my sister. I was masturbating, using my real sister, my blood related sister, as my masturbation material.

“Eh, no.”

My sister’s tone was very flat.

“Huh?”

“Don’t ‘huh’ me. It’s normally unthinkable to even come on your own sister.”

Yeah, that’s probably the normal reaction, but what about a sister helping her brother masturbate? I don’t understand her standards…

“You’re going to cum on a tissue, right? Here.”

Miyu handed me a box of tissues that was always kept on the desk.

I see? So this is reality?

“So, how do you usually do it?”

My sister seemed to know that men cum on tissues, but she didn’t seem to know exactly how. What a biased knowledge. I had to take advantage of this.

“Usually, I hang it on a drawer and cum on it.”

I had never done that before, though.

“Oh, I see. Your hands are occupied with clicking, right?”

Miyu seemed to understand. I didn’t tell her that the auto function would free up my hands though.

“So, if you’re going to help me, it would be helpful if you held the tissue.”

“Is that so? Should I just sit here in front of you?”

Miyu sat cross-legged on the floor, holding a single tissue between her fingers, and spread it out in front of me. It was obviously too thin, but at this point, I was prepared to be scolded. This chance would never come again.

“Alright, I’m going to do it now.”

“Okay.”

I clicked the mouse with my right hand and resumed masturbating with my left. Miu watched me rub my penis without any apparent emotion.

A cute girl younger than me was observing my masturbation right in front of me. This kind of scene was not something you could easily find, even if you paid for it at a store.

I was certain. I would cum twice as much as usual. I would cum on my sister and cover her body with my sperm.

“Aaah… mi… Miyu…”

Taking advantage of the similarity between Biyu and Miyu’s names, I called out my sister’s name as I rubbed my shaft.

I didn’t care if Miyu noticed it. The game’s audio had long stopped reaching my ears.
Miu was looking at my penis. Every time she blinked, the reality of it resonated in my lower abdomen, making my penis even bigger. From the swollen, red glans, a lewd liquid was about to burst out, and I was about to reach my climax in front of my sister.

“Ah… kuh… Miyu… I’m…!”

Ejaculation was imminent. Whether I let go of my penis or grabbed the base, there was no changing the future—ejaculating in front of my sister. Just imagining that moment filled me with a sense of guilt that burned my throat.

“Miyu… I’m… cumming… aaah…”

Immediately, I switched to my right hand and rubbed my penis with all my might. To expel more sperm, to shoot it out with more force.

I could feel the sensation of hot, sticky semen passing through my urethra. The sperm broke through the tissue as I had imagined, leaving its genetic imprint on Miyu’s body.

“Aaah… still… cumming…”

There was no way this climax, having reached its peak, would end with just one ejaculation. Dun, dun, the vibrations echoed from the blood vessels of my penis, and with each one, I shot out a large amount of sperm.

Finally, the spasms subsided, and a sloppy residue of sperm flowed down my shaft from the tip.

“Ugh! You cum too much, Onii-chan. It got on my clothes.”

White, sticky liquid was splattered all over Miyu. She scooped up the sperm that had landed on her cheek and glared at me with her eyes half-closed. She scolded me like it was normal. I felt like the point was slightly off, though.

I was enveloped in a pleasant sense of relaxation, and I wasn’t listening to half of what she was saying.

From then on, an awkward distance remained between us—in fact, it had always been like that—and a few days passed.

An unavoidable situation was fast approaching me.