My younger sister is a high school freshman this year, but her body has already developed beautifully. She stands about 5'5", and her bust is truly striking. Every time she changes out of her school uniform after class, leaving her in nothing but a thin chemise, the slight protrusion of her nipples sends my imagination racing...

We often play around together. Sometimes, in the heat of our teasing, she will scramble onto my lap to wrestle. Occasionally, she accidentally sits a bit too high, landing right on my manhood. She never seems to notice, but it leaves me struggling to keep my composure and prevent an erection.

One time, we had a truly exhilarating experience.

It was a Saturday afternoon, and the house was empty except for my sister and me. Feeling exhausted, I wanted to take a nap, but remembering I had errands to run at five, I instructed her to wake me up. I was wearing a pair of very short boxers when I went to sleep, and the fatigue pulled me into a deep slumber almost instantly. Usually, a man's penis becomes erect during sleep; it happens to me often. This time, perhaps because of a vivid dream, it grew hard again. Because my shorts were so short, my member slipped out from the fabric, standing stiff and upright.

Later, it felt as though someone had entered the room. I wanted to wake up, but the exhaustion was so heavy that my body barely reacted. I had a vague intuition that it was my sister. When she walked in and saw my penis peeking out from my shorts, she startled. She called my name softly, and when she saw no response, she leaned closer to the bed. Suddenly, a wave of intense pleasure surged through my lower body. I jumped internally, but quickly and cleverly feigned sleep. It turned out my sister was gripping my penis with her hand, stroking it up and down!

After fondling me for a while, she hesitated, then leaned down to take my glans into her mouth. She began to slide her mouth up and down, sucking me deep. Waves of pleasure crashed over me, making me afraid to move for fear she would realize I was awake and feel embarrassed. So, I let her play with me. Eventually, the sensation became unbearable, and I suddenly ejaculated right into her mouth. She didn't have time to react and ended up swallowing most of it down her throat! She hurriedly cleaned up with some tissues and then called me awake, pretending as if nothing had happened.

"Good heavens, you just messed with me, and now you're waking me up? If you weren't a girl, you'd know it takes a moment to catch my breath," I said, lazily rolling over and pretending to ignore her.

But rolling over was a mistake. I turned the wrong way, and as it happened, my sister was sitting at the head of the bed. My turn caused me to press down directly onto her hand, and by sheer coincidence, my "meat stick"—still slick with the remnants of my semen—pressed against her. She pulled her hand away quickly. I squinted my eyes to watch; she reached for a tissue to wipe herself, but after a moment of thought, she simply licked it clean with her tongue.

"Sister, what are you licking?!"

"Oh! Nothing, Brother! I just accidentally got some maltose on my hand!" she lied.

"I'm so tired... I want to sleep a little longer..."

"Ha! Do you think I'm a kid? You're so easy to fool," I thought. Exhausted, I drifted back toward sleep.

Suddenly, I felt a gust of air as someone sat beside me. Opening my eyes just a slit, I saw her had returned. *Alright, let's see what trick you have up your sleeve next,* I thought.

She leaned in close to see if I was truly asleep. The sound of her heavy breathing reached my ears. *Oh, you seem quite excited! It looks like that boyfriend of yours has trained you well,* I thought, continuing my charade of sleep.

Convinced I was dead to the world, she began to wander her hands over my body. It felt so itchy and ticklish. I suppressed a groan as she gradually moved lower, reaching my manhood. She began to stroke it up and down. *Mmm, not bad. You seem well-trained,* I thought, my excitement building.

Perhaps because she was still wearing her underwear, her movements were somewhat restricted. Growing impatient, she began to pull my boxers down. Taking the opportunity, I rolled onto my back to lie flat. She recoiled as if startled, but seeing that I remained motionless, she crept back toward me.

This time, she wasn't using her hands; she was using her tongue. *Impressive. You even know this move? I might have to charge your boyfriend a tuition fee for this,* I mused.

Then, she took my member into her mouth, teasing the tip with her tongue. *Oh, that feels amazing...* A fire began to burn deep in my chest.

Her hands were not idle either. She began to rub her own private parts, eventually sliding her panties down to reveal a dark, lush thicket of hair. *Wow, what a magnificent forest. I didn't realize she had become so mature,* I thought, nearly salivating. But now was not the time to act lest we startle the prey. I suppressed my urges and watched her performance.

I figured her boyfriend probably hadn't been giving her much attention lately, leaving her hungry for sensation, and here I was, reaping the benefits.

After a while, she climbed on top of me, straddling my lower body. She began to rub her mound against my penis. *Why don't you slide it in? Do you and your boyfriend play like this too?* Unable to hold back any longer from the friction, I reached out and gripped her waist.

The movement caused her to freeze. We stared at each other in a long, silent standoff until finally, I spoke. "Hey, sister... if you're going to play, you should at least let me know. Are you treating me like a toy?"

"Bro... I... I didn't mean to! I thought you were asleep... so I..." she stammered, trying to cover her tracks.

"Oh? So you were just using me like your boyfriend? What am principal am I to you?" I teased, feigning mock anger.

"S-sorry! What do you want me to do then? I'll pay you back with my allowance!" She seemed to be getting a little annoyed. I suspected her boyfriend might have been neglecting her, leaving her with no way to vent her desire, and now I had become her outlet.

"Hah? What would I do with your allowance? It wouldn't even buy me a can of energy drink. Besides, you just made me shoot once—is your little bit of money enough for that?"

"That's because you don't close the door when you sleep, and you only wear underwear! And that jerk, Aki... he's been missing lately, so I..."

"Oh, so it's my fault? Because I didn't look after your boyfriend, leaving you with nowhere to vent? And because I left the door open and wore only boxers, making you itch with desire? How sinful of me!"

"I... I didn't say that! I just..." She ran out of words, her hands gripping my waist tightly.

"Hey, if you squeeze any harder, you'll leave bruises."

"Then tell me what to do!" she said impatiently.

"Well, you've made my 'little brother' big and hard, and you're asking me what to do?" I teased, squeezing her waist in return.

"Oh, so you're teasing me! Hmph, fine, I'm done!" She turned to get up and leave.

"Hey, you're just going to leave like that? We're only halfway through," I said, pulling her back. "If no one helps you put out that fire, don't blame me."

"Who told you to be like this?" she rolled her eyes at me.

"How am I like this? You started it!" My hands wandered restlessly over her breasts. Finally, the opportunity was mine.

As I massaged her, she leaned in closer, her hands joining mine to work on my manhood. I guided her to straddle me with her back to my face. As my hands and tongue worked on her intimate folds, she began to cry out.

"Does it feel good?" I whispered, reaching forward to cup her heavy, drooping breasts. The position made them look even larger.

"Oh... it's... it's wonderful... Brother... you're so good..." she moaned, her mouth never leaving my penis while her right hand played with my testicles.

"Oh, sister, you're so wet already. Are you craving it that much?"

"Mmm... yes... I want it... I want it..." Without waiting for me to move, she flipped around to sit atop my member. She guided me in, searching for the right angle, and then slid all the way down.

She was incredibly tight. The sensation was almost painful, but it was immediately overtaken by pure ecstasy. I gripped her hips and began to thrust upward.

As if unsatisfied, she moved my hands to her breasts. I understood the silent command and began to knead them. "Ah... ah... mmm... mmm..." She was clearly loving the sensation.

"Let's change positions," I said, sitting up and lifting her legs to rest on my shoulders. Holding her buttocks, I began to pump into her. "Mmm... ah... ah..." she groaned.

After a while, my hands grew tired, so I laid her back down. I lifted one of her legs and slid my own leg between hers, continuing the rhythmic thrusting in a modified missionary position.

"Mmm... Brother, can we change again? Mmm..." She crawled up, kneeling on all fours to signal she wanted me from behind. I guided myself to her entrance and slid in; the angle allowed for much deeper penetration. Waves of pleasure surged through me, and I increased my pace.

"Oh... ah... ah... it's so good... oh..." she cried out. My hands slid forward to squeeze her breasts, which were swollen and sensitive from the arousal.

"Brother... are you almost there? Oh... oh... I... I can't take it... ah... ah... mmm... ah..."

Before she could finish, her vaginal muscles began to spasm around me. I figured she had reached her climax; the cold sweat breaking out on her skin confirmed it.

Because of my previous ejaculation, my response was a bit slower. We continued for nearly twenty minutes before the urge hit me. I turned her over so she was lying on her back, entering her in a standard position to make it easier to finish.

After a few more powerful thrusts, the sensation finally arrived. I accelerated my pace, and her cries grew louder and louder. "Oh... oh... almost... almost there...!" I breathed heavily.

Finally, waves of hot fluid erupted from me, shooting deep into her. A few seconds later, exhausted, I collapsed onto her, my softening member still nestled deep within her.