My Little Sister Is the Best F*p Material

Volume 4 Chapter 01: My Little Sister Doesn’t Try Hard Anymore

The house we bought shortly after my younger sister, Miyu, was born had separate rooms assigned to each of us since we were children. On the single bed in that room, where I’d spent nearly the same number of years since I became aware of myself, I was engaged in my first intimate act with my sister.

“Onii-chan… I’m sorry I couldn’t be honest until now. The truth is… I’ve always—”

Without even a pajama or a single piece of underwear, my sister Miyu and I, bound by blood, embraced each other in our natural state. Miyu’s lips, gazing at me with a longing expression, moved within my blurred vision, clouded by excitement.

My heart pounded painfully, leaving me far from a state where I could sleep. The blood, forcefully pumped from my rapidly beating heart, rushed straight to my groin, hardening and enlarging my penis. In this situation, where our genitals were already close enough to touch, all it would take was a slight movement of my hips for us to begin having sex.

“Miyu… I love you too…! Forgive me for being such a brother… I, I feel the same about you…!”

Overcome by genuine romantic feelings for my sister, I abandoned my responsibilities as a brother. My mind, skipping over the stages of romance, drove my desires forward. My bare penis, without even a thin layer of protection, penetrated Miyu’s vagina, reflecting my weakening resolve. By the time the head of my penis was fully inserted, both Miyu and I were letting out hot breaths. The sense of transgression from inserting myself into my real sister’s vagina without protection pushed my desire to ejaculate beyond its limits even before I started thrusting.

“Miyu… I’m sorry, I can’t hold back at all…!! I’m going to insert it and release inside you… I’m going to ejaculate inside Miyu’s vagina…!!”

It was such an impulsive union that I couldn’t even call it sex. I thrust my aroused penis into Miyu’s untouched female opening, feeling the signal from my brain to ejaculate, and moved my hips as much as my feelings allowed.

“Ahh, haah… Onii-chan… I love you too… I love you so much…!! Ejaculate inside me… Fill my vagina with your semen…!!”

“Ugh, aah…!! Miyu… Miyu…!!”

The semen, released with a cry of utmost love, shot into Miyu’s vagina with the force of a trigger, mixing with the leaking love juices and creating an unpleasant stickiness in the groin area. I continued to ejaculate vigorously while tightly embracing Miyu, and in the midst of it, I felt as if I were floating in the air—and then I woke up in bed. Covered in sweat, despite not having moved my hips even once, the exhaustion and shortness of breath felt exactly like the aftermath of the act.

“Haa, haa… Haa… Seriously…?”

This was already the third time I’d had a wet dream at my age. The sensation of Miyu lingering on my body felt more real with each wet dream, and the amount of semen I released was beyond comparison to the last time, even without checking my underwear.

(What if I moaned out loud…?)

Though it was morning, it wasn’t particularly early. If I’d been moaning as much in real life as I did in the dream, Miyu, who had woken up earlier in the next room, might have heard it. In that case, Miyu would likely come to my room and say:

“Onii-chan, did you ejaculate again while sleeping?”

Miyu, in her pajamas, entered my room as if it were a routine. This wasn’t a dream—it was my real sister. Since the start of summer vacation, this was the second time it happened, so she wasn’t even surprised anymore. And it was the second day in a row after yesterday’s wet dream.

I’d reached a point where I couldn’t even ejaculate anymore without using Miyu, my real sister, as my “material.” However, to return to a proper sibling relationship, I hadn’t asked her to drink my semen after her “I won’t try hard anymore” declaration.

Despite my efforts not to use Miyu as my “material,” the only way I could ejaculate through masturbation was by fantasizing about being intimate with her. As a result, I inevitably ended up on a masturbation ban. Perhaps due to the growing sense of crisis about becoming independent from my sister, my testicles exceeded their storage capacity after just two days, forcing me to see Miyu in my dreams and ejaculate uncontrollably. My sister, who makes me have erotic dreams and ejaculate, started to feel like a succubus.

“So, what are you going to do this time?”

Miyu stood by the door, neither entering nor leaving my room, because yesterday I gave in and asked her to clean up my semen. Of course, that’s not allowed anymore. I’m trying to become independent from my sister, so no matter the situation, I have to handle my semen myself.

“Um, well… I mean, like yesterday, asking you to clean it up by licking… That is…”

“Hmm? Are you going to ask, or not?”

“Uh, uh… Can I ask you to…?”

“Sure. I won’t refuse.”

Miyu closed the door and entered the room. I couldn’t refuse. Miyu was being so forward. Even if she knew I’d had a wet dream, she wouldn’t usually come to my room. Why go out of her way to come to her brother’s room after a wet dream?

If I think Miyu is actively seeking physical contact with me, her actions make sense. But does her statement about “not trying hard to hold back” allow for such a simple interpretation?

“Here, Onii-chan. Lift your hips.”

Miyu, already accustomed to this, removed the blanket and took off my pants. As she sat on the bed and leaned forward to reach my underwear, her hair draped over the sheets, its glossy texture resembling a clear stream. Her chest, shaped into a sphere by her bra and ample breasts, was concealed by the tightly buttoned pajamas, hiding the cleavage. Even in the early morning, her gaze, fixed on my private parts, seemed to be returning to the Miyu of early summer.

I still haven’t fully understood the conversation Miyu and I had on the last day before summer vacation. But it seems that whenever Miyu and I become intimate—though in Miyu’s view, we haven’t actually had sex, and she’s only cleaning up my semen orally—my sexual desire increases to the point where I can’t hold back from masturbating.

Maybe that’s why she was in a bad mood when she woke up that one time. Too tired from masturbating too much. Just imagining this sister of mine, alone and quietly touching her sensitive spots, is incredibly erotic.

“What’s with that look of yours as if you’re staring at something erotic?”

Miyu, preparing to lick the semen around my groin, tucked one side of her hair behind her ear and placed her opposite elbow on the mattress. Facing my semi-retracted penis, covered in semen, she extended her tongue, looking awkwardly at me. If this isn’t an erotic sister, then what is?

“Is there any greater happiness in my life than having Miyu drink my semen…?”

“Stop saying silly things and just stay still while I clean you up… Mm… Heh… Chup…”

“Uhh… Haah… Miyu, that… feels so good…!”

As Miyu’s tongue touched my groin, the warm pleasure spread from my bladder to the area around my testicles. Each time she licked up the semen, she slightly raised her chin and swallowed it, and seeing the movement of her throat as she drank my semen made me feel aroused again, even though I’d just ejaculated.

“Chup… Churup… Nn… Fuu. All done.”

Miyu licked up the visible semen stains and used her fingers to remove any clumps, but she didn’t lick the shaft or the testicles, which were the most covered in semen. Since Miyu has decided not to hold back when it comes to intimate matters, if I were to order her to give me oral sex now, she would obey. However, that would go against the respect I have for Miyu, who has been helping me become independent from her.

“Miyu… um, if it’s okay, could you just… the tip?”

Ah, I’m losing it. My resolve is crumbling faster and faster. I managed to stay firm for a few days after deciding not to get intimate with Miyu, but since our physical contact decreased, my sexual desire has been spiraling out of control.

“What exactly are you asking for?”

Miyu sat up and looked down at me lying on the bed. She glanced at my erection, which was rock-hard despite just ejaculating, and gave me a sharp look, as if I were an insect.

“There’s still… inside… around the urethra, I can feel some left, so… could you suck it out for me?”

When I asked, Miyu closed her eyes, thought for a few seconds, and then grabbed a pillow, pressing it over my face.

“Use this as a blindfold.”

That was her condition for sucking it out. I’ve been through something similar before, and since Miyu’s no longer holding back, if I ask her to do it orally, she will. But I’m still embarrassed to be watched during the act. If I cheat and try to peek, she’ll probably press the pillow over my face until I pass out.

“Got it. Just do it like this.”

Hearing my consent, Miyu lowered herself again to suck out the semen. Then, I felt her fingers wrap around both sides of my shaft, and my penis, flipped downward, stretched. Miyu was supporting my erect penis, pointing it upward.

“Nchu… chu…”

“Ahh…!! Aah…!!”

Deciding not to tease me, Miyu immediately latched onto my urethra. She covered just the tip, not fully hiding the glans, applying pressure only where the semen exits the penis. The rhythmic sucking, like drawing out honey, and the sensation of her tongue spreading the slit, created an illusion in my blindfolded state that I was receiving fellatio. Or rather, it was undeniably fellatio.

“Ah, ugh… Miyu… sorry, really sorry…!!”

I’d just had a wet dream, and the stimulation my penis was receiving was minimal. There was no visual input, and we weren’t exchanging any lewd words. Still, just having Miyu’s mouth on my ejaculation point was enough for my body to feel ready to climax.

“It’s coming… ah, it’s coming, coming…!!”

“Nn…!? Nn…!!”

I injected more semen—byuku, byururu—into Miyu’s mouth, which was sucking out the semen from my urethra. Despite such a brief act leading to orgasm, my ejaculation into Miyu’s mouth didn’t stop, continuing until every last drop was fired. With less physical contact, my body might be thinking it needs to let Miyu drink whenever possible.

“Mm…”

Miyu glared at me with a mouth full of semen. Rather, she couldn’t open her mouth because it was filled with my semen—how lewd.

“Nku… paha… Onii-chan… I knew you’d ejaculate even without stimulation, but what’s with that speed?”

“Sorry… honestly, just releasing into Miyu’s mouth is already so pleasurable for me…”

“You’re an incurable sis-con with premature ejaculation…”

Miyu looked exasperated, though in reality, she wasn’t particularly angry about it. However, as expected, after drinking a large amount of my semen, her libido seemed to be rising. She glared down at me resentfully, tightly pressing her knees together and restlessly rubbing her thighs against each other as if they itched.

“Are… are you okay?”

“I’m not. Take responsibility.”

Miyu extended both hands and leaned forward, pinning me against the bed in a wall-don position.

“Eh…!? Ah, ah…”

What does taking responsibility mean? Does it mean she’ll let me touch her down there? If so, I’ll take as much responsibility as she wants.

“First, wipe that dirty thing and lie down on the bed.”

Miyu instructed me to clean the semen off my penis with tissue and lie down on the far side of the bed under the covers. I shouldn’t disobey Miyu in moments like this, so I followed her instructions. By the way, I never thought using tissue from the start would’ve been better. I’m sure no one would think that. It feels better to have her lick it off, and I believe Miyu wants to maintain some form of physical contact with me.

“Um… my underwear…?”

“Don’t wear it. And put on these earphones, face the wall, and don’t take them off or turn around until I say so.”

Miyu took my smartphone and earphone set from my desk and played ambient music with continuous background sounds. After putting the earphones in my ears, she slipped into the futon with me. I was made to face the wall, feeling only Miyu’s body heat against my back. Her upper body was pressed tightly against mine.

With my pants and underwear discarded on the floor, my lower body exposed, I lay in the futon, feeling my sister’s warmth against my back. Through the earphones, café ambient music from the internet played—light jazz and the clinking of dishes layering endlessly.

Then, I wondered what Miyu would do next—or rather, she did nothing… well, to be precise, I could faintly sense her moving slightly, but she was just clinging to my back. Could it be that simply sleeping together like this was her way of taking responsibility…? I thought for a few seconds. However, there was no way Miyu, feeling aroused, would just lie quietly in the futon. The heat from her back gradually intensified, and her restless movements grew larger.

(This… she’s doing it behind me, right…?)

Miyu deliberately blocked my ears because there’s something she doesn’t want me to hear. Given the flow of events and this situation, I can only conclude that she’s trying to muffle her moans as she masturbates.

Miyu not only clung to me but also pressed her chest against me with such force, even going so far as to sniff the scent at the base of my neck. The breath on the back of my head grew increasingly heavy, signaling that Miyu was likely close to climaxing. After all, she once masturbated while wearing my underwear, so it’s clear she has a constitution that gets aroused by something related to me. But if it’s not romantic love, then what is it?

(Oh no… the earphones are slipping…!)

As Miyu clung to me from behind with increasing intensity, the earphones slipped from my head, which was being jostled around. Completely absorbed in her masturbation, Miyu wouldn’t notice such a thing. But if I heard her and said nothing, it might violate our unspoken agreement. So, I quietly reached up to adjust the earphones—

But Miyu, mistaking my movement for an attempt to remove them, pressed down on my arm. Then, breathing heavily against the back of my neck, her body trembled violently as she reached her climax.

“……chan…!! Nn… nn… n──!!”

The sudden movement caused the earphones to come off, and the serene jazz music was abruptly replaced by the sound of my voice and Miyu’s desperate moans. Even in this situation, Miyu clung to me, pinning my arms down. With her other hand, she continued to touch herself intimately, unrestrained.

“Haa… nn… nn…!! N, ah… aah… naah…!”

Both her hot, moist breath and her sweat-inducing high body temperature heightened my tension. Even if the earphones hadn’t come off, it would’ve been obvious to me what she was doing so boldly. Yet, Miyu was genuinely masturbating right behind me. Instead of sneaking off to her own room, she went out of her way to block my ears and engage in self-pleasure in the same bed. Is this what it feels like when a girl uses a guy as “material”?

“U… fuu… Haa…”

After climaxing and seemingly satisfied, Miyu entered a state of relaxation. Though the earphones had fallen off my ears, she paid it no mind and simply rested.

“Um…”

“What? I’m going to sleep now.”

“……I got hard again.”

“I’m not in the mood anymore.”

Well, that’s understandable. Rather, it’s weird that I’m still aroused after ejaculating so much.

“It can’t be helped, at least hold the tissue..”

Miyu handed me the tissue box and, as if saying “do what you want,” started stroking my erect penis back and forth. It was such a rough motion I couldn’t call it handjob, but for me, just having Miyu do it was enough to make me ejaculate. In silence, lying together in bed, I released my semen into the tissue I was holding.

Miyu, noticing my ejaculation from the twitching of my penis, stopped and fell asleep. I’d done something lewd with my sister again.

“Nn… fuu… Onii-chan… your back’s gotten bigger… faa… ah…”

In a sudden shift to a relaxed atmosphere, Miyu began to breathe softly, falling asleep. What we’re doing is perhaps an obscenely intimate form of physical contact, one that even lovers might not engage in. But once our mutual desires settle, we revert to being somewhat affectionate siblings. Miyu shows such a lovable side of herself, and that’s why I can’t help but love her endlessly.

(I should make plans to meet with Yamamoto-san sooner. There’s no way I can endure things if Miyu can’t hold back anymore.)

Feeling Miyu’s warm body against my back, I reached out to the smartphone placed on the bed board and, with fingers trembling from anxiety, sent a message to Yamamoto-san.