My Little Sister Is the Best F*p Material

Volume 09 Chapter 01: Yamamoto Clinic for Male Genital Treatment (Open 24/7, No Days Off, Exclusively for Sotomichi-kun)

T/N: Hallooo, sorry for the late upload of Volume 9. Just a heads up, this will be the last volume (for now), as I don’t have access to the latest volume, Volume 10, that released just this year. If anyone has it, you can pm me the raws, better if in epub form, so it’s easier for me to work on it. You can pm me on discord, @arrochi. Join the ZetroTranslation discord server to get a mutual server with me.

P.S: There’s a one-shot kind of Light Novel version of this too, complete with erotic illustrations, just one volume. I will do that probably 1 month after I upload the last chapter for Volume 9 if nobody has access to Volume 10, I’ll just make an announcement on the description page so you can navigate to that page.

Since the opening ceremony was on Friday, the weekend became a time for Miyu and me to adjust to our newly settled circumstances. On Saturday, we received souvenirs from our parents, went out for a rare family lunch, and, as night fell, naturally drifted toward having sex again…

“Feeling nervous, maybe?”

“Could be.”

Like last night, we stripped naked, and Miyu started with a blowjob, but my penis was struggling to get hard. The small size pleased Miyu, which was fine, but the issue was its softness.

“So floppy.”

“No idea why. It’s like I forgot how to get it stiff…”

Miyu worked hard, sucking my foreskin-covered cock, and after a long effort, I managed to ejaculate, but without an erection, the semen lacked force, barely a teaspoon’s worth in volume and thickness. Small and soft, insertion was impossible, so I ended the night unable to do anything for Miyu.

Sunday morning showed no signs of an erection either. The sensation of semen building in my balls was faint. Being naked with parents around might not be ideal, so we slept in pajamas, but even gazing at Miyu’s sleeping face only lulled me to sleep, not arousal.

With our issues resolved and Miyu officially my lover, I worried that the taboo-driven lust fueling me had faded. I never knew failing to get hard for a girl could feel so guilty. Amid my confusion, Miyu encouraged me, saying, “You’re just tired,” and we skipped sex that day.

I felt the weight of semen in my groin again on Monday morning, a school day. As I unbuttoned Miyu’s pajamas in bed, touching her underboob and nipples with lover’s privilege, her waking eyes met mine, and my penis twitched in response.

“Why’re you groping your sister’s boobs without permission?”

“Thanks to that, my libido’s building up.”

“Really!?”

Miyu flung off the blanket, instantly ready for action. Was she holding back her desire, or did my arousal spark hers? Either way, her morning eagerness for sex was a relief.

“Three days to recharge your libido? That’s rare.”

“Probably just came too much.”

I showed her the tent in my pants. Miyu looked thrilled at first but soon frowned.

“Hm? Onii-chan, take it off.”

At her urging, I dropped my pants, revealing an erect penis—not thumb-sized but worthy of being called a cock. Still, it lacked the usual vigor; despite being hard, it wasn’t as robust, noticeably smaller in girth and length.

“We can probably do it, but… was yours like this?”

“No, it used to be bigger.”

“Hmm. Maybe it’ll grow while I suck.”

I lay back on the bed, and Miyu moved to my feet, starting with a blowjob.

Amu… ngu… chuu… pa. “Ahnmu, nmu… jururu… chuu…”

Miyu, now skilled at blowjobs, enveloped my cock in pleasure, swallowing it to the base, her tongue gliding along the shaft.

“Oh, ah… feels different, but… good… really good…!”

Her lips took my hard rod deep, and her erotic face as she licked my groin was insanely arousing. I love a girl with my cock stuffed in her mouth, so this size wasn’t bad, but…

“Nn… nnn… chubu… hero, chuu… ah, nn… fumu…”

After sucking thoroughly, Miyu pulled off with a kyupo, and my cock sprang out, regaining its hardness but not its former size.

“This might be its limit. It just reaches my throat when I take it to the base, so it’s much smaller than before.”

“Guess so… what now?”

“It’s gentler on my body, and I enjoy it. Can you put it in?”

“Sure. Missionary?”

Miyu lay back, and with only our lower halves bare, we started sex in missionary. Without the hassle of a condom, my raw cock slipped into her vagina.

“Nn… ah…”

Miyu’s moan at insertion signaled I hit her favorite spot. Her tight slit made even this smaller cock feel snug. Despite all our sex, how’s her pussy still so pichipichi tight? Like Yamamoto-san, Miyu’s body is uniquely erotic in its own way.

“Your pussy’s so wet and warm, Miyu. Good thing you’re ready.”

“Fuu… nn, your cock rubs my insides just right… different from before, but nice in its own way…”

My shorter cock hit her G-spot easily, and simple pistoning without angle adjustments brought her noticeable pleasure.

“Fuu, haa, ah… Miyu…!”

I sped up, thrusting into her vagina. Normally, I’d hold back from going too deep, but slamming my hips fully felt exhilarating.

“Nnah, aah… Onii-chan, it’s intense… nn… feels good…!”

Miyu seemed to find special pleasure in rapid thrusts, her pussy making lewd picha picha sounds. Even my premature ejaculation seemed improved, and I kept pounding her in the short morning time.

“Ah… haan… Onii-chan… Onii-chan…!”

“Miyu… I’m cumming… gonna cum…!!”

“Haa, nn, yeah… ah… but… school’s soon…! Haa, nnah… ah, ah… creampie, nnah… aah!”

“Miyu, sorry, can’t hold it…!! Cumming… creampie… haa, uh…!!”

I unleashed a massive load into her vagina, enveloped in triumph and pleasure, ejaculating deep inside. I kept my raw cock in her until the twitching stopped, catching my breath, and kissed her. Miyu blushed shyly.

“Ugh… I wasn’t thinking either… a creampie right before school…”

“Sorry, it’s been a while, so I had to cum inside you.”

“I didn’t want it outside either, so it’s fine.”

Miyu sat up, pressed her stomach to squeeze out semen onto a tissue, then went downstairs to shower. Morning showers aren’t her habit, so our parents might suspect something, but we can’t sweat the small stuff now.

(Haa… we had sex… but…)

Washing my face at the upstairs sink, I changed and waited for breakfast in my room. Mom’s cooking morning and night for a while, apparently.

This morning’s sex was the passionate, loving kind I’d idealized. But it didn’t sit right. For Miyu’s petite frame, this size is ideal, especially for daily sex to avoid straining her. But after a three-day break, the sex and her reactions felt lackluster.

Maybe it was the short pre-school time. Still, as a guy, I want to dominate a girl with a mighty cock. Did Miyu even cum?

Curious, I went to her room after hearing her return from the shower.

“—Yeah, I might not have cum.”

Brushing her hair, Miyu answered my question casually.

“Cumming’s exhausting, though. You make me cum till I pass out sometimes.”

“Right, that’s tough too. Sorry.”

The more a guy chases pleasure, the more it burdens a girl’s body. It’s an unavoidable trade-off, so sex should prioritize the woman’s comfort—at least for typical couples.

“But, honestly…”

After some talk, Miyu shyly confessed her true feelings.

“It felt a bit lacking.”

This sex was satisfying. Even a smaller cock felt good.

But compared to before, it lacked intensity. For us siblings, mere pleasure isn’t enough. If this level satisfied us, we wouldn’t have needed to become lovers as siblings in the first place.

“Let’s ask Kanade-san.”

“That sex goddess might have a fix.”

For sex troubles, Yamamoto-san’s the go-to.

“But, like with the prep school thing, doesn’t it bother you that I rely on Yamamoto-san?”

“Nah, it’s fine. I’m your girlfriend.”

Too strong. That one line erased my hesitation.

“Then I’ll ask for advice.”

With a clear head, I headed to school. Thanks to the weekend, no one questioned why Miyu and I skipped the same day as Yamamoto-san, and I faced a normal second semester.

“As you know, next year’s your exam year, so this is your last break. That’s why the school trip’s now. Form groups with whoever you want and have fun.”

The homeroom teacher’s words stirred the class. A school trip’s fun depends partly on the teacher’s mood, and random group assignments via lottery can ruin it, so this was lucky news. Still, these groups are for the field trip’s history museum visits, not free time, which has no size limit. We’re not elementary kids anymore.

Right, a school trip. A four-day, three-night one. Great for students, but for Miyu and me, four days without sex?

Will we be okay? Gotta discuss this later.

“Sotomichi, just us three guys—me and Takanami, cool?”

Right after homeroom, Suzuhara spoke up. Sticking with the usual crew makes things easy.

“Just guys?”

“Huh? Oh, you were absent, so you don’t know.”

Our school’s gender ratio is even, so the class splits roughly equal. Field trip groups divide into six, so three groups of six guys and three of girls make sense.

“Look over there.”

Suzuhara pointed to a classroom corner where a mixed group of three guys and three girls formed.

“They called it a ‘pure field trip triple date’ and made a mixed group. Now, if others stick to same-sex groups, some get left out.”

“What a hassle…”

This sparked a trend toward all mixed groups, with guys and girls subtly negotiating pairings. What were they planning if the teacher had used a lottery?

As someone with a partner, walking with girls sounds like a pain. I don’t want to argue over lunch spots.

“Gotta be Yamamoto-san, right? Let’s get her to bring cute girls.”

Takanami joined, naming the one everyone’s probably eyeing.

Just so you know, she’s half mine.

“You cool with that, Suzuhara?”

“No problem. Wanna show off my upgraded self.”

“How’d the mixer go?”

“Takanami got a girlfriend.”

Suzuhara reported, and Takanami pointed a proud thumb at himself. Calling for Yamamoto-san despite having a girlfriend? Jocks are too flashy.

“And I scored too.”

“Nice.”

“…With Harumaki-chan.”

“Got it. Don’t need details. Spill on the trip if you want.”

Good for him. Suzuhara’s gotten smoother with girls and looks better for it. Something happened.

“How ‘bout you, Sotomichi?”

“Just hung out.”

“With who?”

Suzuhara pressed, and a long-haired girl cut in from the side.

“With me, right, Sotomichi-kun?”

Yamamoto-san’s words cracked the classroom’s atmosphere with a sharp piki.

She went there.

“We bumped into each other at a concert, and turns out we share some hobbies.”

“Yeah, that’s right, totally.”

“Then we went karaoke together.”

“Uh-huh.”

All we did was have blowjobs.

“Are you two dating!?”

Takanami was the most shocked by Yamamoto-san’s statement. Surprisingly, Suzuhara listened calmly.

“Not dating.”

“Nope, not dating.”

We’re not dating. Had tons of sex, though. My lover’s Miyu, my precious little sister.

“No clue what’s going on, but if you’re not dating, Yamamoto-san’s fine joining our group, right?”

Takanami seized the moment. That drive probably got him his girlfriend.

“Sure, sounds good. …Nanako, you’re okay with it?”

Yamamoto-san turned to ask, addressing Kawafuji Nanako, someone I’d briefly connected with over summer break. Her neatly trimmed bob and sharp gaze still carried an icy chill. Unlike Miyu’s dry demeanor, hers screamed “stay away unless you’re needed.”

“You’re still hanging out with unpopular guys who can’t get boyfriends?”

“It’s not about being popular or not. Besides, haven’t they all leveled up since before summer?”

Kawafuji’s jab included Suzuhara and Takanami, and the three of us exchanged tense greetings. Suzuhara’s changed the most—sharper features, calmer vibe. Takanami’s supposedly gotten smoother with girls, but it doesn’t show. He was always the best-looking among us, just a goofy otaku inside.

“I’m fine as long as Kanade’s with me. Who’s the last one?”

“Hm, didn’t think about it. What now?”

Yamamoto-san gets along with everyone, so her ties with other girls don’t vary much. She doesn’t have particularly close friends, so we need one more. Her gaze shifted to the seat next to mine.

“Eh, me?”

Yup, Onozaki (小野崎). Glasses, braids, Onozaki. The last spot could’ve been a guy, but girls blend easier into mixed groups.

“You’re close with Sotomichi-kun, right?”

“Not exactly…”

Right, not close. We only talked because of Miyu’s orders. She’s easier to chat with than other girls, though.

“Doesn’t Onozaki have a group already?”

“I did, but the mixed-group trend messed it up. My original group fell apart. If I can walk with a guy I like, I’d rather do that.”

Another victim of the trend. Those who started mixed groups deserve some karma. I thought our class wasn’t big on romance, but the unspoken vibe must’ve kept crushes hidden. Plenty of people like each other, it seems.

“So, Onozaki’s with us, then?”

“Fine by me. It’s a mess with guys I like overlapping. Just give me an excuse to join.”

At Onozaki’s suggestion, I checked with the others. Suzuhara, silent till now, spoke up.

“If that settles the six, I’m good. I’d drag Onozaki in if I had to.”

“Onozaki! Join us! It’ll be a blast!”

“I’m inviting her, so she can’t say no!”

“Better than adding another dumb guy.”

Unanimous agreement sealed the final spot. The morning’s excitement turned to anger and sadness by afternoon as groups formed, and I was glad we locked ours in early.

The school trip group didn’t interest me much. I had more pressing matters. I’d messaged Yamamoto-san beforehand to meet after school. Thanks to her bold friend declaration, we could talk without drawing attention, but the only place for us was the usual reference room.

“Feels nostalgic.”

“Our first real go at it was here.”

“Didn’t think I’d fall for you this hard back then.”

Yamamoto-san flashed a soft, melty smile, unlike her classroom composure, openly showing her affection.

I locked the door, and we grabbed chairs, sitting side by side against the wall by the stacked file cabinets.

“I’m just as shocked.”

A nobody like me, liked by such a cute girl, and as someone special for life, no less.

“Trouble’s about sex, right?”

“Exactly as you guessed. …Feels like the same old consultation.”

“Can’t get it up again?”

“Yup.”

I laid it bare: I can get hard and ejaculate, but not with my old vigor. My stamina and semen volume are noticeably down.

Yamamoto-san listened, nodding with a half-hearted “hmm” like she wasn’t thinking hard, then started unbuttoning her blouse from the bottom.

“Wanna grope my boobs for starters?”

This girl’s always eager to have her boobs touched.

“Uh, is that okay?”

“It’s not cheating to grope a bit. Come on, slide your hand in, go wild.”

She unbuttoned half her blouse, lifted it with her camisole, and pulled up her bra. Her heavy, plump breasts spilled out, topped with perfectly shaped, puffy nipples like bottle caps. So erotic, I instinctively looked away.

“Your body’s just… too hot, Yamamoto-san…”

“You know every inch under my clothes.”

Fanning her blouse, she gave me a sultry look, urging me to grope her.

“Probably a hundred guys passing me today wanted to strip and worship these boobs. Don’t you want to grab them with smug satisfaction in a private school spot?”

“Only you’d be this blatant about school hookups.”

She knows exactly what guys want. Honestly, I was turned on. Miyu probably foresaw this when she suggested consulting her. Hesitating here would be rude to Yamamoto-san.

“Nn… your hands are warm, Sotomichi-kun…”

I slipped my hand under her blouse, groping her breasts. Amid the distant shouts of after-school club activities, I savored the rustle of her blouse and the overflowing softness of her boobs. Even teasing her nipples, she stifled moans, but her abs twitched under her lifted hem, and her flushed, loosened face was utterly lewd. My erection strained my slacks.

“You’re hard, Sotomichi-kun.”

She unzipped my pants, exposing my cock, carefully avoiding the shaft—her line, I guess. Peeking through the open fly, my cock was bigger than this morning with Miyu, though not at its peak.

“It’s got some hardness too, right?”

“Feels like I’m getting my groove back.”

Boob-groping cock therapy worked fast. Yamamoto Male Genital Clinic’s got instant results.

“Were you excited when you had sex with Miyu-chan?”

“Uh, not sure.”

The loving sex wasn’t bad, but Miyu seemed less thrilled, and I wasn’t as hyped as usual either.

“I think I’ve got a hunch about the cause.”

Standing, without fixing our clothes, she told me to stand too.

“Can we do something a bit naughty?”

“Uh, yeah.”

What was the boob-groping then? Just a greeting?

As I pondered, Yamamoto-san loosened her skirt, dropping it and her panties to her ankles. Her hairless pussy peeked out, one hand lifting her blouse to show her boobs. The sight made my cock throb hard.

“So erotic…”

I muttered, and she looked pleased.

“It got a bit bigger, huh?”

She smirked at my cock. To think it was just about my excitement level—such a simple fix.

“Your pussy’s always so smooth. You shaving daily now?”

“Actually, I started permanent hair removal.”

“Permanent? Like, never growing back?”

For someone as mature as Yamamoto-san, pubic hair would be natural. But her perfectly shaved pussy screams deliberate choice, bound to stand out at a hot spring.

“Yup. It depends on how many sessions, but… I wanted my body to stay just how you like it. Might go all the way.”

“You love me too much.”

“No one I’ll ever love more.”

She let me ogle her pussy, then dropped her skirt and panties to the floor. A lewd schoolgirl in just a disheveled blouse, naked from the waist down.

“No matter who I date, I want my body to show I became a woman through our sex. I’ll make sure not a single hair grows back.”

Lifting her blouse, she spread her legs wide, flaunting her pale, laser-lightened bald pussy.

“It hurts like being seared by fire during sessions. Feels like swearing loyalty to you with a slave’s brand… it’s so arousing. I caused trouble for the nurse.”

Her light tone belied the hardcore kink.

So erotic, my heart’s pounding painfully. No one would guess the pure, princess-like girl from class is irreversibly altering her body for one guy.

“Maybe I shouldn’t say this, but… I’m really touched.”

Sure, it’s because she’s a stunning beauty. But as a former otaku, knowing the universally kind Yamamoto-san, a beacon for loners, is dedicating her body to one guy hits my balls hard.

“Hehe. Hearing that makes it worth it.”

Maybe she’s just indulging her desire to serve. But for a guy whose dominance fuels pleasure, her report alone could make me cum.

“Now, let’s do something naughty.”

She leaned in, my cock tip barely grazing her naked lower half, and sucked on my ear.

“Nn~ chuu… jururu… chupu… haa… Sotomichi-kun… make your cock big…”

“Nn… aah… ngh—!?”

The sudden pleasure buckled my knees, and I collapsed. Her lewd pussy flickered under her blouse hem.

“You’re staring at my embarrassing parts, Sotomichi-kun… Your cock’s twitching like crazy.”

“Ah, yeah, this is…!”

I couldn’t stop staring at her pristine bald pussy. She spread it with her fingers, kupaa, revealing a raw, glistening slit like a sliced fruit. Her laser-enhanced vagina was practically art.

“Hehe. If you didn’t have a girlfriend, you could’ve licked it all you wanted.”

“Talk about regret.”

“If Miyu-chan allows it, maybe in a few years.”

Such a filthy conversation, yet her voice bounced playfully.

“But it’s not much bigger, huh? This might be my limit. Shall we go to your place and let Miyu-chan fix it?”

After making her suggestion, Yamamoto-san added, “And I’ve got a solution in mind.” Here comes another naughty turn.

“If my penis stayed this size, what would you think as a girl?”

“I wouldn’t care at all,” Yamamoto-san said, placing her index finger on her lower lip with a smile, answering without a hint of hesitation. The emphasis on “I” was so very her.

“Even if it got so small it couldn’t enter my vagina no matter how hard you tried, I’d study blowjobs every day to make you feel good. As long as your balls have sperm, we could even make a baby.”

She said it with a refreshing smile. Being truly loved by Yamamoto-san feels like this. Not even my lover, yet what a blissful sensation.

As I marveled, she straddled me—mind you, my erect cock’s still out of my pants, and she’s naked from the waist down, one small dip away from raw insertion. Then she licked my neck and teased my nipples through my shirt.

“Besides, you can always find new erogenous zones…”

“Nn, nn, nnh, nnn…!!”

“It’s twitching again, leaking from the tip… Cumming would be cheating, though. Gotta hold back.”

What kind of rule is that? I couldn’t even quip back—her tongue and fingers felt too good. Without her warning, I’d have cum already. Devoting all her lust to one guy makes her this erotic?

“I’m really gonna cum, stop…!”

“Aw, too bad. I love your moans.”

She finally pulled back, checking my cock, which hadn’t grown much despite being on the verge of bursting. Our little experiment in the room paused there.

She got me cold water, which I pressed against my cock to calm the blood flow and kill the erection. Pointlessly, she drank the water herself. Pointlessly. Then we slipped out of school discreetly to meet Miyu at my place.

Yamamoto-san’s slyness lies in her experience and confidence—she doesn’t see guys as status symbols. If she were a pure virgin, “I don’t care if my boyfriend’s small” would sound like a line from a girl secretly banging a well-hung playboy. Her greatest charm in our sex life might be how safe it feels to be unconditionally devoted to.

“Was all that really okay?”

“Don’t worry. I did it on purpose. You’ll see when we get to Miyu-chan.”

She gave off a mysterious Miyu-like vibe. The reason became clear the moment we reached my house.

“—W-What… nn, ah… what’s going on…!?”

In my room, Miyu’s top was off, breasts exposed, with Yamamoto-san teasing her nipples from behind. What’s this situation?

“It hasn’t even been a week, and this again…!”

“That’s what led to now. Your boobs are still big and cute, Miyu-chan.”

“Nn… nnh… hia…!”

Yamamoto-san toyed with Miyu’s breasts with a sleazy, old-man grin. Unlike a sister or mother doting on family, there was no lesbian sensuality here. Her sticky teasing felt like a perverse father molesting his daughter. Utterly obscene. By the way, I was half-naked, my cock hard from Miyu’s ravishment.

“Look, Sotomichi-kun’s fine cock’s getting bigger. Like I said, the issue’s with Miyu-chan, right?”

“This is… nn… a problem too…!”

“No biggie. Sotomichi-kun groped my boobs too. This much isn’t cheating.”

That’s why she did that pervy stuff in the reference room. No, both sides have issues here—mutual misdeeds don’t cancel out. Compared to Miyu’s calculated strategies, Yamamoto-san’s impulsive, momentum-driven approach was so her.

“Miyu-chan, you gotta work on exciting guys. Like showing him you masturbate.”

“No way, I’d die first.”

“Then show a cuter side.”

Yamamoto-san mercilessly pinched Miyu’s nipples. Her precise pressure, honed from some secret playtime, left Miyu writhing under relentless pleasure.

“Nn, nnaa, no…! Any more, and… an, aah…!”

“Cumming would be cheating, Miyu-chan. Try harder.”

“No… ah, ah, I’m gonna cum…! No, nooo… aah, ah… it’ll be cheating…!”

Miyu bought into Yamamoto-san’s bizarre cheating rules. When hyped up, her brain goes as wild as Yamamoto-san’s.

“Aa… hia… aaah—!!”

Despite resisting, Miyu came quickly. Even after, Yamamoto-san kept groping her boobs and blowing on her ears, making her cum repeatedly.

“Miyu-chan, cumming so easily… Okay with this, Sotomichi-kun? She’s cheating.”

“Uh… yeah…”

Do whatever. I can’t keep up with your ethics. Even seeing Miyu do erotic stuff with Yamamoto-san, all I feel is arousal. They’ve twisted my kinks, damn it.

“Hehe. Miyu-chan’s all ready, and your cock’s back to normal. I’ll leave you lovebirds to it.”

Releasing Miyu, Yamamoto-san quickly prepped to leave, stepping out the door.

“If you two aren’t all lovey-dovey, I’ll be upset.”

“No need to tell us, we’ll be plenty lovey-dovey from now on.”

“Good to hear. Have at it, then.”

Chased by Miyu’s accusing glare, Yamamoto-san descended the stairs. Miyu stared out the window, waving as Yamamoto-san headed home.

“Phew. What an erotic woman.”

“I got a fresh reminder of her sexiness.”

“She could at least stop dragging me into it… Anyway, shall we have proper sex for the first time in a while?”

Brushing off her multiple orgasms with her usual “whatever” attitude, Miyu turned to me. But my cock, once hard, was softening again.

“Huh? Why?”

“No idea. It was fine just now…!”

“Whatever, I’ll suck you. Onii-chan, try to get it back.”

Miyu hurriedly knelt before me, popping my cock into her mouth.

Jururu… chuu… nchuu… juru, jubu… nku…

“Oh… ugh… feels good…”

Maybe because my cock’s thicker, increasing contact in her mouth, the blowjob felt better than yesterday. But it was far from its biggest, and though pleasurable, the hardness kept slipping.

“Nn… n, juru… jubu… haa, ugh… Onii-chan, just a bit more, put in some effort.”

“I know, I’m trying.”

When feeling external stimulation, sensitivity isn’t constant even when erect. From the moment something clicks toward ejaculation, sensitivity spikes until release. If I could hit that track, I could regain hardness.

That was our shared understanding. I forced an ejaculation response to rouse my cock. It swelled and hardened back to normal. But—

“Uh, ugh… sorry, Miyu…! I can’t hold it…!”

“Nn… ngu… jubu… fe? Eh, wait… amu… nn…!”

Byu, byu, byu—! I came mercilessly. Normally, I could control it at the edge, but forcing an erection from a soft state meant I could only cum after hitting max hardness.

“Ugh… nn… It finally got big…”

“Sorry.”

Normally, one ejaculation wouldn’t deflate me, but this time, my cock shrank even in Miyu’s mouth.

“But thanks to Yamamoto-san, we know if I get excited enough, it’ll work. Let’s try again tonight.”

“Right. This is a wall we have to climb together.”

Miyu didn’t lose heart, and we decided to seriously tackle my premature ejaculation issue. That night, maybe because I’d cum so little in her mouth, I soon felt the signal of semen building in my balls again.

My balls ached, and I had the urge to cum. My body clearly wanted to have sex with Miyu. It’s probably just that the intense stimulation from the threesome with Miyu and Yamamoto-san threw off my senses. But the afterglow’s so strong that if I wait for time to fix it, Miyu and I might go months without proper sex.

“So, can I ask you something, Miyu?”

“Let’s hear it.”

That night, we gathered in my room again. Fresh from her bath, Miyu sat on the floor in her usual silky pajamas, kneeling formally.

“I want to grope your boobs too. Yamamoto-san said excitement’s key. If that’s true, I really want to grope your boobs.”

I mustered the courage to spill my feelings.

Miyu closed her eyes, processing my words, then nodded slowly.

“Got it. You can do whatever you want with my boobs. Grope them, suck them.”

“For real!?”

“Y-Yes.”

Her quick agreement sent my heart soaring. Was it Yamamoto-san’s advice? I never expected permission to do anything I wanted.

“Maybe I haven’t been self-aware enough as your lover. I should’ve let you have free rein with my boobs. I’m sorry.”

Her ears reddened as she spoke earnestly, word by word. Letting me do whatever with her complex-inducing huge breasts showed the depth of her love for me.

“I’ll make sure it doesn’t hurt.”

I unbuttoned her pajamas. Starting from the top of her curved chest, I slipped each button through with both hands, revealing her collarbone under just her bra with each release.

Removing the pajamas, I reached for her bra’s clasp. Her cute, lace-trimmed, custom-made bra supported her massive breasts, which swelled even more once freed. Her nipples, daintier than Yamamoto-san’s, greeted me cutely.

“Feels like I’m stuck in shame play today.”

Miyu braced herself, hands on her knees, ready for nipple stimulation. I lifted her heavy breasts and lowered my head to suck on her nipple.

“Nnn…!! Ah… ugh…!!”

“Nn… haa… Miyu…”

Facing her sensitivity, I flattened her breast’s tip, taking the protruding nipple fully into my mouth, flicking my tongue up and down.

“Ah, ah, ah…!! Onii-chan, that’s… no…!!”

Each lick made Miyu twitch, and my cock swelled in sync. Despite their softness, her huge breasts held a sturdy weight, and when I sucked hard with a juru, she moaned in pleasure.

“Aah, aahn… like that, hia… Onii-chan, too into it…!”

“Nn… fuu… It’s just, you’re letting me suck your boobs… it’s like a dream…”

Holding her breasts with both hands, I sucked her right nipple, then her left, over and over. Like gorging on junk food, I messily sucked her boobs, licking obsessively as if savoring every drop from a straw, tormenting her.

“Haan, aah… gonna… cum…!! Cum… cumming… cumming…!!”

Like a dam breaking, Miyu climaxed. Overwhelmed by my tongue, her body gave out, muscles spent. I lifted her waist and pinned her to the bed.

“Miyu, I’m hard. I’ll suck your boobs while I fuck you.”

“Haa, haa… wait… let me… rest…”

I stripped off her clothes, shed my pants, and thrust out my rock-hard cock.

“Onii-chan, wait, if you put that in, I’ll scream too loud.”

“Then let’s do it under the blanket.”

My lust was unstoppable. I covered Miyu, pulled the blanket over us, and we continued in our makeshift soundproof cocoon. Lifting her legs, which dangled sloppily off the bed, I knelt on the floor, leaning over to slide my cock into her.

“Haa, haaa… Miyu… Miyu…!!”

“Nn!! Nnuuu… ah… nnNN…!! A-Ah, Onii-chan…!! No, ah, intense… cumming… I’m gonna cum…!!”

Pan, pan! Pounding my hips, I listened to Miyu’s muffled screams under the blanket, driving my cock like a stake. Her breasts jiggled with my thrusts, and sucking her nipple while hitting her womb’s depths made her arch her back and cum hard.

“Ah, aaah, aah, nooo…!! H-Hii, feels too good… nn, ah, nooo, no, no…!! Ah, aah… aah!! Oh, hya, ah, cumming, hiii… aauaa…!!”

The sensation of prying open Miyu’s vagina, a euphoric pleasure, enveloped me. Knowing I had the right to ravish her boosted my pride to dizzying heights.

Juru… ju… “Haa… Miyu… I love you… I’ll love you forever…!! Gonna cum inside… Miyu…!!”

“Aaah… nnaauaa…!! Inside… I love… aaahh…!!”

Byurubyururu, byukubyuku, dopu, dopun, dopu—!!

Sweat flew in the blanket’s heat as I shot a massive load into her vagina. Exhausted, I collapsed, savoring her chest’s rise and fall as I caught my breath.

“Fuu, haa… stupid Onii… sucking my boobs too much… making a girl cum too much… but I love you…”

“I love you too, Miyu.”

We shared a love-filled kiss, then, wrapped in post-sex fatigue, hugged naked on the bed, kissing until we passed out.

The next morning:

“Seal my boobs.”

In her uniform, Miyu’s breasts strained against her blazer as she declared this. Naturally, within a day, her “do whatever” permission was revoked.

“Why?”

“Getting my boobs sucked feels too good. I’ll go crazy if this continues.”

“That’s… fair…”

I couldn’t argue. I knew I’d gone overboard.

“You’re fixed now, so you’re fine, right?”

“Not troubled, but it’s not permanent, is it?”

“Just go with the flow. I won’t get mad.”

“Right.”

Basically, no sex with boob-sucking without prior permission. Knowing my sister, if I begged on my knees—gross as she’d find it—she’d probably let me. But as a guy, I need to learn how to set the mood for sex.

“By the way, Onii-chan.”

Miyu, her straightened hair down to her waist, gazed at me with innocent, wide eyes despite last night’s wild sex.

“Hm?”

“You only came once yesterday, right?”

“Yup.”

We only count thick, full loads, so one’s correct.

“So, after days of no proper release, by this morning, you’re loaded up again, right?”

“Should be.”

“Then your kind little sister will suck you off.”

“Oh, wow. That’s bold. I’m thrilled.”

Yamamoto-san effect? She’s learned the need to please a guy for our sex life.

“Well, uh… I’ve been swallowing thin stuff for a while.”

“Oh, that’s it.”

This doll-like sister secretly craves my thick, bitter semen that sticks in her throat. Whether she loves blowjobs or not, she wants my proper load. Too embarrassing for her to admit, but our conversation confirms it.

“Go for it.”

I half-dropped my pants, exposing my cock. After breakfast, before school, we’re doing a sibling blowjob. My loli, busty sister was supposed to make me cum… or so I thought.

“Uh… Onii-chan?”

What’s this? My cock wasn’t getting hard. The erectile dysfunction I thought was cured last night wasn’t fully healed.

“Uh, well… maybe I’m tired again…”

I scrambled to explain, but Miyu, who’d been so hopeful, puffed her cheeks, eyes tearing up in frustration.

“Mmuuu…!!”

Such a cute face, craving my semen.

“I got the knack yesterday! So, let’s try stuff… like, uh, paizuri, or changing locations!”

I stayed positive. Knowing it’s not all my fault, Miyu picked up on my enthusiasm.

“Or we use that as a last resort.”

“No, let’s save that. It’s not ready for you yet.”

“Right.”

She’s really thinking about us. I can’t let her down.