"Ah, what a pain..." A grumble at nothing in particular, Kirino cracking her neck as she strode down the last street before home. Pain. The dull, satisfactory pain of muscle ache resounding with every step taken. A minute 'pulsation' carrying equal parts pain and pleasure, one of a runner's high attained mere hours before. Pain. What a damn pain. 

The sole minute solace of the usual school day came in the form of the schedule. A shortened day. Half the schedule cut clean off for whatever reason or another; it wasn't in her demeanor to really question why a school day had decided to castrate itself so. It was luck! Just dumb luck! Why not take that in stride, wonder about the day in general.

The day...ah, right. She did say that earlier today. A day like any other? Maybe. Yesterday was the same. Same for the day before. The weekends. The holidays. Same as always. Save for...that closeness. Kirino could hear the giggles as clear as day. Her mother and her stepsister laughing with each other when they thought no one else was watching. The sly glances. The subtle turns of her mother's hands, rewarding her stepsister (that brat) with a free extra pieces of chocolate on Valentine's, a few extra bills on New Year's, on and on...They were (un)lucky that Dad was always on some business trip nowadays. Moreso than usual.

Back on track, back on track...Stepsister. Lil' Sis Rika. The vaguest thoughts in her mind poked at their first meeting, one's quickly discarded by her current concerns. Closeness. When did it start happening? She just looked closely one day and...and it was just there. No rampup. One day, Rika and Mama were as usual. The next...as close as two people could possibly. No, closer? Kirino didn't have much experience in this area...she was only fifteen, for crying out loud. But her nine year old sister, even closer? Nah, it must be exhaustion...

That's what she kept telling herself, anyways. 

Today was slightly different in that regard, anyways. A surge of courage made her ask Mama to tell her exactly what was going on. Nothing too explicit; she didn't even know what was going on between the two. Just... "What's going between you two!? Tell me!" And her sis had the gall to step in and just say "Wait until tonight!" with that high-pitched voice of hers. God, when did they get so close like that!? It was low-key infurating, but everything was on the table...and lucky her, she didn't say there was a half-day today. Today, she'll learn the truth...!

"I'm home!" The usual exclamation made upon entering the house, the golden sunset coating the room in a regal yellow. Nothing unusual here. Just...silence. Scratch that, something was unusual. Quietness. Not the idyllic kind, but the unnatural kind that begat a surprise. "...Hello?" Further into her own house. Tch, why was she feeling this way!? It was a surprise, a surprise! Maybe they were sleeping. Or doing something like they always did! Or, or something!

And yet.
And yet.
And yet.

"Hello!? Oi, are one of you around!? Mama! Rika!" Tch. Ah, who really cared. She'd call Mama after taking a nap. A quick bound up the sta- her door was ajar. She always left it like that, for sure. But...but that didn't explain the goosebumps crawling up her neck. The slight metallic taste of dread in her mouth. She'll learn. That was what Rika had said. Learn what? This?

A step. Another step. Socked feet muffling her steps, instinctively walking with a light step.

"Hglrck..."
A pause.
"...Mama?"
"...Ghlrh hlrk hlrk hlrk hlrk...!"
Those wet, sloppy noises of unknown origin. As if something, or rather, someone was being filled. Another step.
"GHLRK...H-HRRRK...!"

Step after cautious step towards the door, Kirino barely breathing by this point. Anticipation. Creeping horror. Dread. All these emotions whirling inside her as she dared to peek through the sliver of open space, gazing upon the scene inside.

"...!?!" 


Her Mama. Her sister. Both were in her room. Sis on the bed, mama...in front her? Kneeling? Why was...why was Mama's head down at her sis's crotch? Why was she topless? Why was she wearing only jeans? Why why why wh- Why was Rika naked? Why was she...what was she doing to Mama...!?

"GHLRK...Nghrk...Phaa..."

And then Kirino's world shattered. Her sis. Her happy go lucky sister, one with purple hair down past her shoulders, had...h-had...that dick. That monster. Behemoth. Word after word failing to describe the monster that was currently being slathered with her Mama's saliva. "Mi~ That hungry tonight, mama? That's fine, three shots is nothing." 

Kirino could only watch on in abject horror. Her mother, topless with jeans. Her sister, naked and sporting a demonic-looking dick. The meatspire slowly having the grace of delicate, experienced digits tap up and down the length, black lipsticked lips layering marks of utter devotion on to the best. "Yes, Rika...We can't do this for much longer, please..."

"No." Rika's own voice assumed an uncharacteristic coldness, grabbing a lock of the MILF's hair and smashing her face up against the rugged sack. "I'll have you pull off when I'm satisfied like always~ And then we'll show Kirino her surprise when she gets home, okay~?" Such a cheerful voice contrasting against the rough, near-bestial motions underneath, Mama struggling for a few seconds before settling in a regular rhythm; kissing, licking, stroking.

All Kirino could do was watch. Watch, and barely note the bag on her shoulder sliding off and crashing against the ground, the obvious cacaphony unmistakably alerting the duo. "...Mi~ Kirino? You can come in anytime. Surprise surprise, this is what we've been up to all this time!"

...

H-how did it come to this?
Why was she knelt in front of her sister?
Why did Mama get so insistent?
Why was Rika able to command her so easily?
Was that why Kirino was knelt down in front of the hung stepsister, tears openly flowing as her throat undulated in protest of the thick meatslab buried inside?
Was that why Mama had Kirino's pinned behind her back, her other hand forcefully bobbing her dear daughter's head back and forth like an onahole?
Was that why Rika was acting like it was business as usual?

"Haa...You know, Mama, I didn't expect you to say yes so easily!" Rika was completely nonchalant about having one girl educate another, leaning back for Kirino to bury her face onto the spotless crotch. Oooh, there was another gag, another wave of saliva to coat the sack and everything below it. How messy of this blonde.

"It's only fair to show her what she's been missing." Mama dug her fingers into the roots of her daughter's hair, pulling off to the tip before slamming back down, wet PLAPS of saliva splashing forth with the protests of Kirino's body. Back and forth, again and again, the black lipstick marks refusing to loosen themselves from the rugged, unnaturally muscular length of the stepsister. Kirino's eyes were wide in fear, unable to process the situation at hand. Rika. Cock.

Cock.
Cock.
A fat fucking schlong that one could only dream of in the throes of puberty. The obscenely flared head allowing for a natural stopping point on the forced deepthroat, a few unnatural bulges along the length pressing against her throat with ease. Every downthrust brought her to the hilt, where equally bulky cumtanks plowed against her stained chin, forcing another explosion of saliva to coat everything below. Heated. Hot. Dense. Kirino's pupils were dialating in utter fear, squirming her hips every so often to attempt the start of an escape.

It didn't take much for every attempt to fail.

"Phaa...H-h-h-hhhhh-hhhhaaaaa..." Kirino was finally pulled free of the hell she had been subjected to, her burning lungs dry heaving in an attempt to fill her blood with the precious oxygen that it had been deprived of. Shuddering, twitching, her vision fading in and out as the worries of the world escaped her addled mind. "Hah..HHACK...H-Hah...Mama...Mama..."

"Mama's right here."

And she was jolted back into reality.

"Please...no more...Mama..."

As the slab swung down onto her face, Kirino could understand that her protests were in vain for the night. Understanding didn't mean that she stopped muttering for help, but it did take away from the fact that the brutal throatswabbing had nearly cleaned Rika's length of those black marks. A stepsister who was staring down at the two with the eyes someone much older than the mere age of nine.

The night had only begun, after all.