When my sister Kumiko got admitted to Kitauji High School, she began bringing home girls from her music club, and each time I'd be subjected to hearing their noisy sex from my room on the other side of the wall.

This baffled me for a while. Kumiko had hitherto been a quiet girl. Where had this libido come from all of the sudden?

What's more is that Kumiko knows I arrive home from work before her, so she either doesn't care that I hear her banging her friends every day for nearly two hours, or she wants me to hear it.

I initially dismissed the latter theory because, well, she's my sister. However, a week or two ago something changed in the way she talked to me. She would assume this monotone voice, almost like that of a robot mimicking human emotion, and would slip in innuendos aimed at me whenever we talked.

I figured I was just imagining things, but for some reason she won't stop smiling. Minutes on end, Kumiko will stare at me almost expectantly, as if her head is filled with dirty thoughts. I made the mistake of looking directly at her one time. I won't forget the hunger I saw in her eyes, like that of a baby tiger catching prey for the first time.

That was the first night the dreams started. I'd dream of Kumiko making love to her friends until suddenly I was the one underneath her. This dream persisted for weeks, and each time I'd wake up with the image of Kumiko smiling etched into my head.

Something is wrong with me, I thought. Of course the next day Kumiko brought home yet another girl whose moaning and screaming I was forced to listen to for a good two hours. The same thing happened the next day as well. And then the day after that. And the day after that. Even when the weekend rolled around, Kumiko's adventures never let up.

It was quickly becoming a logical equivalent that if our mom was at work, Kumiko was in the bedroom. If mom got off work at night, Kumiko got off in the afternoon. If mom finished early, so too would Kumiko.

I tried blocking out the noise with earplugs and headphones, but nothing worked. Everywhere I went I could hear the slapping of skin against skin and the pleasured cries of women being brought to orgasm by my sister.

My ability to distinguish fiction from reality was growing duller by the day. I'd wake up to my dreams and still hear moans echoing through my walls. It was getting so bad that I began to question whether the two of us had done something forbidden in a past life that was now coming back to haunt me.

I was half expecting I'd wake up in a psychiatric ward where I would learn that I went insane one day and attacked my sister while we were out bowling or something.

"Nee-chan," she'd say in that robotic voice of hers. "Nee-chan. Nee-chan. Nee-chan." And then I'd pounce and rip off all her clothes in one fell swoop. I'd force her to say my name again. "Nee-chan. Nee-chan. Nee-chan."

Such a reality always seemed distant to me.

At least, that's what I thought until yesterday.

A customer yelled at me at the register. I took it, because it was my job to take it, but that still didn't stop the manager from chewing me out afterwards. It was my fault, she told me. It was my job to be at fault.

I came home volatile. I wanted to run. I didn't know where to, but anywhere was fine if it was just for a little while.

Before I could change into something lighter, however, I heard the click of the front door opening, and soon after the robotic voice of my sister talking to some girl named Reina.

Reina. She had come here before. No one else had ever come home with Kumiko twice before until now. Why? Was she one of Kumiko's favorites? Had she become smitten with some skank from school? What if she was her girlfriend?

Girlfriend. Something about that word rubbed me the wrong way. How come they get to be all lovey with each other while I get yelled at by my boss? Why couldn't I fool around with my classmates after school instead of working some shitty dead-end job?

But the thought that raced through my head the most was why I couldn't be Kumiko's girlfriend? Why did I have to be her sister? Why couldn't I have been born into another family so we could make love the way she did with her friends? It wasn't fair. None of it was.

I heard them move into Kumiko's room, and against my better judgement I put my ear to the wall. Within seconds I could hear Reina gagging on Kumiko's cock. Then I heard it again and again and again and again and again and again and again and again and again and again and again until I lost it.

I reached into my shorts and took hold of myself. I rubbed up and down the length of my cock as if my life depended on it. So overwhelmed was I that I couldn't even bring myself to grab a tissue before I came all over my hand.

I brought it up from my shorts and stared at it. A small puddle of semen spilled over my palm. My head spun so fast. Without thinking, I drank all of it while pretending it was Kumiko's.

My head spun even faster. I sprawled myself onto my bed and lowered my shorts. Again, I stroked myself, revelling in the sensation. The more pleasure I felt, the easier it became to rationalize my perversion.

Slowly, I resigned myself to my fantasies and began moaning her name. "Kumiko! Kumiko! Kumiko!" I bit my shirt to muffle my voice. "Kumiko! Kumiko! Kumiko!"

It was then my door flung open. My heart died. There, in the doorway, stood Kumiko. She saw everything. My shorts and panties hung around my feet. My hand gripping my erection and the leftover traces of semen from my earlier orgasm. But most pressing of all, my voice. Oh god, my voice. What if she heard me moaning her name? She would know all about my lust and my fantasies. Would she hate me? She would have to hate me. What if she told mom?

Every scenario that ran through my head filled me with remorse. Any chance at a normal, sisterly relationship was dead in the water. I prayed for the remote chance that I would open my eyes and exit another one of my dreams where we were regular, familial siblings.

Instead, Kumiko smiled. She smiled, and I felt something sinister wash over me.

"Nee-chan." Her voice was robotic. She must've been thinking something perverted. "Nee-chan." she said, "do you have any condoms?"

I blinked. It dawned on me just then that Kumiko was wearing nothing but her underwear. I pulled up my shorts and walked over to my dresser where I had stashed a box of condoms back in high school. Only two of them were ever used, a fact which, when compared to my little sister's sexual exploits, was quite pitiful. Nevertheless, I retrieved a condom from the box, and then felt something press against my lower back. Next thing I knew, Kumiko scooped the box from my hands.

"Keep that one," she whispered, closing my fingers around the condom, "you'll need it for later."

And then she left me to stand, petrified, in my room where I listened for what felt like hours as Kumiko savagely fucked her friend on the other side of the wall.

The image of her standing in her underwear refused to leave me. At the time I was too frightened to register the tremendous bulge protruding from her groin, but now it seemed unreal to me.

And then it hit me.

The something which had pressed against me earlier was that bulge.

I fell to my knees. I couldn't help myself.

I masturbated again.