Onii-chan saimin chapter 1

Chapter 1 (Oneshot)

(……what the heck is this situation?)



Absolutely weird

What the heck is this situation?

……no, wait, calm down.

For now, calm down and have a deep breath.

*Suuhaa*, *suuhaa*.

Yoshi, then let’s try to remember.

I’m Aiba Ryo

I just became 18 a few days ago.

The one in front of me is Aiba Yuika.

2 years younger than me, 16-year-old.

My blood related sister.

Until now is alright, I remember precisely.

However, the problem is from here.

The problem is why we are in a situation like this.

In other words――

Why Yuika is naked…and collapsed in front of me, I’m similarly naked…and lying on top of Yuika……like riding her.

Moreover, etto……I hurriedly separated, but until a while ago, well……I was connecting with Yuika, and from there, a large amount of white thing began to overflow……, moreover her whole body was covered with white liquid………


E? Why? Why, why!?

No, calm down, calm……how can I calm down!

I don’t know the meaning, I can’t understand.

Certainly, Yuika is cute, if we weren’t siblings……such thought didn’t appear just once or twice.

I didn’t see Yuika as a sister but a woman, and I…….well……also used Yuika as a side dish, but…… (side dish = fap material)

Even so, I intended to cherish her as my only sister, I didn’t think I would commit such a mistake.

But, don’t tell me, I did such a thing……

No no, chill out, me.

For now, let’s calmly remember what happened today.

It was summer vacation, and to make it worse, today was Sunday, I who didn’t have anything special to do stayed at home with Yuika.

Our parents are working, so every day they won’t return until it’s late at night

Therefore, they shouldn’t be at home right now.

……or rather, I would be troubled if they were

My life is over.

……let’s calm down one more time

Right, today is a day off.

I woke up early then spent the morning doing nothing but relaxing, after that I ate the lunch Yuika always made.

Then after that……right, certainly……――




「Onii-chan, are you free today?」


Ou, what’s wrong?」


「I made something triffle as a summer vacation’s research project, but I wonder if Onii-chan can check it for me?」




Yuika says it’s something triffle, but she is (looking from my perspective) a genius.

She handles everything flawlessly, I don’t see anything that she couldn’t do.

Cooking is her forte, the result of her study is top-notch, she can also work-out and is skillful at games.

What did that flawless Yuika make, I wonder?

I remember when we were young, I became engrossed with a popular robot anime, so Yuika reproduced that robot using card board boxes (the overall length was about 150cm) and gave it to me as a present.

What kind of fantastic idea will appear……?

I was driven by the throbbing of my heart as well as a small amount of anxiety


「Then, what did you make?」


I asked as soon as we reached Yuika’s room.

As a room without any special decoration, the interior of the room has almost nothing other than necessities, it can be said as a plain room.

Since I’m hasty, Yuika answers while smiling wryly.


Etto, I made a simple movie. It’s really short, about one minute long though……」


Hee, isn’t that amazing?」


Even so, I will watch the video properly.

Because my friend also made movies, I also heard many stories about the hardships, so I more or less knew the dificulty of making a movie.

Therefore, I was really curious about what kind of work she made.

Yuika sits on the desk and starts her PC.

The preparation seemed to be done, I was beckoned.

I sat on a prepared chair and looked towards the PC.

On the screen, there was an opened file, and inside it was a movie.

I wore the headphone Yuika gave, then she controled the mouse and the movie began to play.




「……chan,……… o……chan


I feel like I’m being called from somewhere far away






My body sprang up *biku* because of the astonishment

Looking at the direction of the voice, my eyes meet Yuika’s

The black hair that covers the shoulders, the big, beautiful, opened eyes and the glossy, glittering lips.

My heart springs up *dokun* and the throbbing is loud and violent.

My gaze is attracted by Yuika’s face and being glued to it, I can’t even turn my face.


「Onii-chan, the movie ended, so what do you think?」


E……a, aa……


Being told so, I finally stop looking at Yuika and turns my gaze to the screen.

Certainly, the movie ended.

However, its contents doesn’t enter my head at all.

It feels completely like I immediately slept when the movie began then woke up just now.

As I’m unable to reply, Yuika calls out to me worriedly.


「Onii-chan, what’s wrong? Are you alright?」


I look at Yuika’s face

As expected, I can’t look away, similar to a while ago.

I couldn’t think properly, it was like my head was covered with mist.

Like my body is being manipulated by someone, it begins to move arbitrarily.

I stand up from the chair and firmly catch Yuika’s shoulders


E? Onii-chan, what?」


Yuika looks at Ryo’s eyes while being bewildered. (suddenly, PoV change)

Then he suddenly kisses Yuika’s lips.


nn!? n……nchu, han, nnーー」


Yuika is still surprised

Perhaps, her thinking couldn’t catch up with the fact that her lips were snatched abruptly.

Ryo’s tongue opens Yuika’s lips and breaks into her mouth, doing whatever it likes.


nn, nーー, n~~……puha


One can’t breathe while kissing.

Yuika turned her face and released her mouth, then exhaled roughly.

Her cheeks are tingled with red, her eyes are moist.




「Onii-cha……n, nnーー」


Once again, our lips pile up.

This time, I hug her tightly to not let her escape.

I entwine my tongue with Yuika’s, then suck it


nn……nchu, chu, chururu……nn, n, nnnーー」


Because of the difference in height, Yuika slightly stands tip-toed and looks upward, she closes her eyes and receives the kiss

Ryo slurps and caresses Yuika’s tongue with his lips and tongue.

Together with a *chupa* sound, their faces separated.


「Onii-chan, don’t」


Averting her face while saying so, Yuika quickly slips out from my arms.

She pulls my hand and lead me to the bed.


「Onii-chan is tired, you know? You should lie down a bit and calm down」


It seems like Yuika thought my eccentric behavior just now was because I’m tired.

Saying so, she comes near the bed and lightly re-arranges it.

Looking from behind, Ryo can see her butts swinging like inviting him

Such a sensual appearance of Yuika, my lower abdomen swells as if it understands

I lifted the fluttering skirt Yuika is wearing and tightly held those lovely butts.


Hyaa!! O, onii-chan! What!?」


Yuika is surprised and hurriedly tries to hold her skirt down, but her balance is broken and she seems to fall, but she somehow withstands by placing both hands on the bed..

The posture where she pushed her butts out too much has completely destroyed Rio’s last reasoning.

He pulls the pure white panties down and digs into her butts.

He then rapidly kisses the lovely, exposed buttocks.


E!? Hyan, o, onii-chan. What are you doing?」


Yuika has a perplexed voice

Without minding that, I kiss her and stimulates her vulva by tracing along it on the panties.


nhyaa, w, wait, onii-chan……n, a……no, don’t~~……hyaun


Yuika twistes around and tries to escape, but her butts are grabbed tightly whenever she does that, so she’s unable to escape.


「D, don’t……Onii, chan…………that’s, aan


The charm in Yuika’s voice gradually increases.

The vulva rubbed by my finger became a bit wet.

The vulva became wet and soaked the pure white panties.

I take off the panties forcefully.

When I stroke the puffing up, beautiful vulva with my finger, a transparent liquid sticks to it.

Then, my tongue crawls into her vulva, as if to lick away that liquid.


nnnnn~~, don’t, that’s no good, onii-chan……please, I beg you……a, aan


I spread out Yuika’s vulva with both hands and peek into the vaginal hole which has a tingle of red.

Every time my tongue licks it, a sweet voice leaks out from Yuika’s mouth, her secret place also twitches *hikuhiku*


a, nn, a, good……feel good……it feels good, onii-chan」


The transparent viscous liquid overflowing from Yuika’s secret place create a string connecting with Ryo’s tongue.

Ryo puts his mouth to Yuika’s secret place and sucks it, making a *jururu* sound.

When my mouth was separated, Yuika’s secret place became sticky with love juice and saliva.

I just noticed at this late hour, but Yuika didn’t seem to be able to put strength into her body, her upper half was lying on the bed, her legs were standing on the floor but the knees were trembling *gakugaku* and her butts was pushing out.

Seeing the shaking as if  pleading butts, Ryo threw away his trousers and pants and took out his penis which was on the verge of exploding.

Putting his hardened penis close to her genital, Ryo rubs it there to tease her.


Haahaa……na, e, w, wait Onii-chan!? That’s no good!?」


Yuika tried to cover her important place with her hands, but before she could, the penis pushed oven the vulva and penetrated inside.


n! a, aa, aaaaaaaaaaaaaaa~~~!!!」


The glans enters completely.

Just with that, the sensation of being crushed attacks the penis.


Haahaahaa……did it, enter……?」


I smile to Yuika who is breathing roughly one after another and thrust my penis.

It slowly advanced inside and soon entered to the root.




A soundless scream leaks out from Yuika’s mouth.

Yuika’s inside is hot and tight, it feels good.

Due to the sensation of being pressed hard, I began moving my hip while enduring the pleasure which would arrive soon.


「Don’t, Onii-chan……your dick is, aaa~~n……I said don’t, i……a, an, an


My penis rubs Yuika’s inside with a relaxed movement.

Every time it pokes her inside, Yuika’s body trembles *biku*

Feeling excited from the sensation from my penis, I quicken the pace and swing my hips.

Waves of pleasures surged forward whenever I thrusted my hips, and my penis soon reached its limit.


Ha, ya……a, n, a……an, n


When I shook my hips remarkably strongly, my penis pulsated *dokun*, *dokun* and released a large amount of semen inside Yuika.

As if to say it’s not enough although it just finished ejaculating, my penis is still hard and doesn’t wither.

Still inserting my penis inside Yuika who is adjusting her rough breathing, I help her stand up by embracing her from behind and put both her hands on the wall.


「Onii-chan……it’s still hard……and big」


As my penis is still inside her vagina, Yuika also seems to understand.

She only turns her face to me and begins to talk.

Her expression was sloven, and the eyes seem to be intoxicated.

While thrusting my penis from behind, I grabbed her breasts.


Hyan, n, a……ii, an, aaa~~」


Her breasts are moderate, but they have nice elasticity. That sensation is soft and feels good.

It seems like the severity of having her erect, throbbing nipples pinched is too much, Yuika’s body springs up and the meat wall wrapped up my penis tightens *kyuuuu*

Ryo’s penis already swelled up.

While kneading Yuika’s nipples with his fingers, the movement of his waist is accelerated.


u, un……aan, a, an, nnn~~~」


*panpan* the sound of meat colliding with each other resounds.

Yuika once again feels the heat of being filled by a penis.


nn, nー……a, onii-chan, onii-chan……onii-chan, aaaaaa~~~」


Yuika’s rough breathing leaks out,as if she just came.

The vaginal wall coils around and stimulates the penis.

At the same time Yuika came, she reunited with the slow piston which stopped before.


「D, don’t, don’t……I, I’m cumming, I’m cumming so don’t……more than this, I will become strange, aan


Despite saying “don’t, don’t”, Yuika herself pushes her butts out and holds the penis deep inside, her vagina strongly tightens and doesn’t release the penis.

When I smoothly caressed Yuika’s bended backward back and lightly hit her pushed out butts, a sweet voice leaked out from her mouth, her body trembled *biku* like springing up.

I stop touching Yuika’s nipples, tightly grasp her waist and violently swing my hips back and forth, starting pistoning.

The short black hair sways violently without a pause.

The limit of my endurance is crossed because of the squeezing pressure of Yuika’s meat wall.


yaa, something amazing, don’t……onii-chan, something amazing is coming, don’t……wait, onii-chaaaaaaa~~~!!」


I pour my hot semen into Yuika’s deepest place.

Yuika’s pussy also tightens *gyugyu*, as if to resonate with the *bikubiku* pulsation of my penis.

At the same time I released inside Yuika, she powerlessly leaned against the wall.


Haahaa……haa, Onii-chan……you came a lot, didn’t you?」


With a somewhat befuddled face, Yuika asked Ryo while breathing roughly.

Together with Yuika who can’t put power to her body and staggers, we collapse onto the bed.

I pull my penis from Yuika and turn her face up.

When I glide my hand on Yuika’s hairless, smooth and beautiful skin on her genital area, the smooth feeling is so good and my gaze is drawn in.

Then right under that, as I extracted my penis, a large amount of semen mixed with a small quantity of blood flow down *dorori*  from the gaped open vagina (sfx: thick/muddy/gooey)

I insert my penis on which those are sticking to to Yuika’s mouth.


a……peni, npu……n, ngu, nchu……njurururu


Even after finishing licking the viscous liquid sticking to my penis, Yuika continues to hold it in her mouth.

Yuika uses her tongue to stimulate the glans and slurps *chuuu* the remained semen inside.

After being taken out, the penis which seems to slightly wither swelled up largely after being stimulated by the mouth.


na……nkupuha……fufu, Onii-chan’s, semen……」


Yuika uses her finger to move the semen sticking to the corner of her mouth into it.

After properly mixing the semen with her tongue as if savouring it, she gulped it down *gokun* and turned toward me with a smile.

I lightly kiss those lips and insert my penis into her still open genital, which is overflowing *torotoro* with semen and doesn’t have any sign of closing.




The glans is burried together with the *nupu* sensation, and my penis pierces deep inside just like that. (I don’t know what *nupu* sfx means tho, it appears many times in all R-18 novels in this site)

Coquettish voice leaks out from Yuika’s half-opened mouth.

Different from what happened until now, this time we are facing each other so whatever expression Yuika has is in full view.

Even if that face is befuddled, it will stir up my lust

While rubbing Yuika’s breasts, I move my waist relaxedly and start pistoning.


「Yuika, cute」


Becoming befuddled and unable to think, Yuika tries to cover her face with both hands as if she noticed her face was being watched, but I only use my right hand to stop her hands by holding them over her head.

She averts her face in order not to let me see her expression, but her face from the side is also lovely and charming, I think about wanting to look at it forever.


ya…..yada, don’t, look……an……don’t look, Onii-chan, n


Even if she pleads me so, there’s no way I would stop looking

While thoroughly look at the erotic expression I have never seen before, I swing my hips.

While enjoying the soft sensation of Yuika’s breasts, I move relaxedly and only use the tip of my penis to attack the swallow part to tease her.

Dozens of second, or perhaps several minutes, after teasing her like that for a while, Yuika gradually begins squirming, I know that her vagina also moves *guniguni* (sfx: soft, like jelly)


nn~a~, don’t~……don’t~、more~, Onii-chan, more~~」


Perhaps because she’s irritated, Yuika moves her waist and begins to plead.

When she turned her averted face to me, that face has an expression filled with worldly desire.


「more, you said? What do you want?」


I say a bit sadistically, but Yuika’s eyes becomes slightly teary as she pleads me.


「Please! Please fill me with your dick more! Please thrust inside me more! I beg you, don’t tease me……」


Satisfied with Yuika who pleads like she has gone mad, I embrace Yuika and stab my hard penis deep inside with all my might.




Yuika raises her loud, gasping voice as her body springs up *bikun*, *bikun*

Yuika also put both hands and both legs around Ryo’s back and embraced him

Yuika’s smooth skin and soft breasts stimulate his lust.

Yuika’s girlish aroma and her heavy breathing leaked from her mouth stimulate his sexual desire.

And more that anything, the vagina wrapping his penis stimulate the pleasure.


「Inside, inside, feels good, Onii-chan……onii-chan’s dick, feels gooooooodddd」


Using my penis, I push it deep inside and rub it from all directions *guriguri*

Perhaps because we are glued, I know that Yuika’s body trembles repeatedly due to the pleasure, what she feels is transmitted more than before.


「a, inside, guriguri feels good……dick’s guriguri, feels goooooooooooodddd!!!」 (guriguri = sfx for grinding)


Yuika gradually becomes unable to speak articulately.

I block her opened lips with mine.

We begins to exchange each other’s breath, then exchange each other’s saliva.

We are having a kiss where our tongues entwine as we deeply desire the other person.


n~~……n, nn,……nchu, nn~~~chu, chu


I slowly pull the penis until it’s on the verge of falling out, from the position where only the tip is buried, I push it inside in one go.




Each time I push, Yuika’s leaked heavy breathing resonate in my ears.

Mixed in the *panpan* sound of colliding meat from the joined part, an obscene *guchuguchu* sound can be heard.


a, good, gooddd, Onii-chan……nnn


I raise the speed of my hip piston and knock Yuika violently like crushing her on the bed.

As if to say it will absolutely not release, her vagina tightens onto my penis *gyuu*


a, aa, ii, an, cumming, cumming, cumming」


I can feel my semen rapidly filled up.

Ryo’s penis becomes big and seems to ejaculate soon.


「Yuika, I’m cumming」


a, onii-chan……me, me too, cumming, cumming, with onii-chan’s, dick, I’m cummingggggggg~~~!!」


Just before ejaculating, I thrusted my penis deeply inside Yuika’s vagina, as if using my glans to kiss the mouth of her uterus.

Together with the *dopyudopyu* sensation, a large amount of semen I have held back up to now is poured into Yuika’s uterus.

Because the meat wall wrapping up my penis coil around as if twisting *gyuu* to the point that it hurts and move to squeeze out the semen, my ejaculation can’t be easily stopped and the semen is wrung out.


「…………ha, ha, haa, haa……」


Yuika resumes her rough breathing, which was stopped when she came.

The power in her embracing arms and legs weakens, she opens her half-closed eyes to look at Ryo’s face.

Yuika’s whole body lost its power, she became exhausted as she immersed in the afterglow after climaxing.


haahaa……n, onii-chan……it felt good」


It seems like it has settled down to a certain extent.

It’s still possible if she’s like that.

The penis which is still inserted inside Yuika slowly begins to move again.


nno, onii-chan, a……are we doing it again?」


「Of course. Let’s have lots of sex」


When I mutter so to Yuika’s ear, the vaginal meat wrapping my penis pulsates *kyunkyun* and the clamping gets stronger.


Un. Please come a lot. Onii-chan」


Yuika also whispers to my ear.

My penis reacts to those words.

I can do much more.

While thinking so, I pushed my penis inside Yuika.





I remembered.

In the end, I came 4, 5 times after that.

I look at the clock

If my head is normal, I can see that 8 hours have passed since I came to this room.

In other words, I have ravished Yuika for one third of a day.

Because of that, Yuika’s body which becomes sticky with sweat and semen trembles repeatedly, her eyes lost their focus and small 「Onii-chan」 murmur can be heard from her mouth.

To such appearance of Yuika, contrary to the thought of condemning myself “what the heck did you do?”, my heart throbs *doki* at Yuika’s appearance which originally shouldn’t be seen.

I shake my head and throw away my boiling up desire

For now, I must do something about this situation.

I picked up a wet towel and jumped out of Yuika’s room.






While seeing the figure of her brother jumping out of the room, Yuika is immersed in the afterglow

Being vented his really hot love and sexual desire, she was really satisfied.

Certainly, there are intense pressure on her stamina as well as her body, but more than those, she was happy and glad.

Stroking her stomach, then she moves her hand to the lower abdomen, scoops up the drooping semen with her finger and licks it

It was really warm, a flavor that satisfied her heart

Naturally, her smile becomes visible.

The sensation of having a foreign substance filled her lower abdomen and the semen sticking all over her body are the best evidences that they were connected.

The *dotadota*  hurried sound can be heard from the other side of the door. (noisily, especial the sound of feet)

*gachiri* the door was opened, onii-chan entered the room as expected.

Just after seeing my figure, he immediately do a dogeza and apologizes for violating me against my will

I beckoned Onii-chan to tell him to come closer, then with my powerless arm, I drew Onii-chan’s face close and lightly kissed him.


「Next time, treat me more gently, okay?」


The *pokan* face of Onii-chan after hearing that was very funny. (dumbfounded)










―――――Going back to what happened a few hours ago.

As the video ended, I removed the headphone from Onii-chan’s head.

Onii-chan is still stupified, his gaze is pointed at the empty space.

As it went smoothly, the feeling of relief and anticipation, excitement or delight are all jumbled together.

The video I used has the effect of using the light and sound to make a person fall into hypnotic condition.

Moreover, from the moment one began to see this video until the order was made, all the memories would be omitted.

Because it differs depending on the person, being unable to setting up the concrete effective time is a fly in the ointment, but…… (玉に瑕, a scratch on a gem/fly in the ointment = something flawed)


Maa, father and mother will return late,  it’s OK to set it moderately long, right?)


*kusu* I let out a smile like a little devil, my chest swells just by thinking what will happen from now on.

I know that sometimes, onii-chan is looking at me with the emotion more than to just a little sister.

I also know that when he masturbates alone in his room, he uses me as a side dish.

Even if other people were drawn away, I was honestly happy about those thought of my beloved onii-chan.

I also think if it’s Onii-chan, I can let him do any thing, I will also do anything he likes.

However, onii-chan only treats me as a little sister.

Onii-chan treats me gently as someone really precious.

Because of that kindness, Onii-chan won’t make a move on me.

I know that this feeling of mine is not normal.

Therefore, I――

To onii-chan’s ear, I quietly yet strongly whispers, filled with affection.


「Onii-chan’s desire, vent it on me. Everything, every~thing, let them out. Vent it on me a lot, please」


For now, is it the time?

I also feel like wanting to look at this stupefied face, but I change my mind as it’s foolish to reduce the time we do it from now on.

When I clap my hands in front of Onii-chan, his body trembles *biku* and he closes his eyes, his head falls down.

While clapping Onii-chan’s shoulders *ponpon*, I try to wake him up


「Onii-chan, wake up. Onii-chan」


――How about doing something verrrrry good with me?

Onii-chan saimin

Onii-chan saimin

Score 7.8
Status: Completed Type: Author: Released: 2017 Native Language: Japanese
When my consciousness returned, I have violated my sister many times


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