After waking up in the middle of the night feeling thirsty, you make your way downstairs to get a drink of water.

Reaching the bottom of the steps, you hear a soft, strange cry. A tender female voice drifts in from the next room, barely audible above the low hum of the AC. You peer around the corner and see your sister Riko, wearing only an oversized t-shirt and lying face-first on the couch with her butt up in the air. The t-shirt is bunched around her upper-torso, leaving her lower half completely exposed.

Both of her arms are reaching down between her legs, with her right hand moving a sharpie in and out of her dripping pussy, and her other desperately rubbing the top of her pussy.

There's another moan, more distinct now that you're closer but still muffled as you see she's moaning into the couch cushions to dampen her voice. Most of her face is hidden, but you can see her eyes are glazed over in a sexual frenzy.

SNAP

The floor settles slightly under your foot as you shift position, leaning around the corner to look more closely.

She jerks her head in your direction. Seeing you there, her eyes widen and she freezes, her slick grip slipping from the marker enough that it pushes out of her onto the couch, a trail of fluid dripping down after it.

The sudden sound of your voice snaps Riko back to reality--she jumps off the couch and almost falls over trying to cover herself with her arms as best she can. Her face flushes red as embarrassment floods through her, making it hard for her to breathe. The sharpie drops from her pussy, leaving a trail of clear pre-cum on the couch cushion where it landed.

"Uh... nothing! I was just... thirsty..."

The heat in Riko's cheeks intensifies as she realizes the double entendre of your words. Her face contorts briefly, torn between shame and amusement at her own predicament. She tries to play it off casually. "Oh... haha, yeah..." She smiles nervously, then turns away from you and starts toward the kitchen. "... just thought I heard something outside or something."

You walk past Riko into your bedroom, flipping on the light as she follows close behind. She shuffles over to sit on the edge of your bed, still trying to cover herself with her arms. The faint glow from the hallway lights casts enough illumination for you both to see each other's face clearly.

"Look... I don't know why I did that..." she starts, biting her lip nervously. "I just... I can't help it. I need..."

Riko glances over at your bed, then back up to meet your eyes. She swallows hard and slowly begins to slide off the edge, her body pressing flat against the mattress as she lies down on her back with her knees bent and spread wide. The smooth flesh of her inner thighs glisten in the dim light from the hallway, and a faint musk fills the air between you.

Her breath comes faster now, her chest rising and falling rapidly underneath the oversized t-shirt. "I just need...

You reach out to gently push apart Riko's knees, spreading her legs wider on your bed. Her sex comes into view, slick with arousal and surrounded by a thin halo of pale curls. The musky scent intensifies as you draw closer, hovering over her exposed pussy like a predator about to strike.

She lets out a shuddering breath, her eyes closing tightly as she tries to steel herself against the oncoming pleasure. "Please..." she whispers hoarsely. "Just...

Without any further warning, you plunge your fingers into Riko's wet, warm pussy. Her body arches off the bed with a moan, her back bowing and her breasts jutting upward as she thrusts her hips toward you in desperate seeking of release. Your fingers curl and stretch inside her, seeking out her sensitive spots as they move in and out in a slow, steady rhythm.

Riko's hips buck beneath you as she feels your fingers inside her, her body shuddering with every stroke. Her moans fill the air, mingling with the sounds of your breath and the slapping of skin against skin. She reaches down between your legs, gripping your hard length through your pajama bottoms, guiding it toward her needy opening.

"Yes..." she gasps, arching further upward as you lick and tease at her folds. "Please... I need it..." Her fingers tighten around your shaft, urging you closer, her body already dripping with desire for the forbidden fruit of incest. She parts her legs wider, offering herself to you completely.

You slicken your cock with Riko's saliva before positioning the head at her entrance. She moans loudly as you push inside, filling her tight, wet channel with your thick length. Her body trembles around you as you begin to thrust, driving deeper with each stroke. The mattress squeaks beneath you as your hips meet, your bodies grinding against each other in a primal dance of lust and desire.