I broke off the top off the ampule, the way I’d seen Rin do.  It took the space of three breaths to build up the nerve, but then I downed it all at once.  The stuff didn’t taste too bad actually.  Like raspberries, that are just a little fermented.  Licking some off my lip, I turned to look down at the tiny girl before me, found her staring back up with a smile of anticipation on her adorable face.

The sensation came on suddenly – something like static electricity, or the feeling you get when your foot falls asleep, but over my whole body.  It took a moment to realize I was moaning, and I made myself stop.  Rin held her hands to her mouth for a frozen moment, as she waited to see which way the dice would fall.  When she pulled them away, she was grinning wickedly.  “Oh,” she said.  “THIS is going to be fun.”

I opened my mouth to ask what she meant, but only ended up moaning again.  I was already beginning to see the evidence of what was happening.  My pants were getting so baggy.  My shoes felt enormous on my feet.  The kitchen counter was rising higher and higher by the second.  And Rin’s smile was growing the fastest of all.

My hands clutched at my clothes, stupidly trying to hold them, like I thought that could keep them the same size.  No such luck.  “Maybe…maybe I’ll only lose a few inches,” I mumbled

“Uh-uh, cutie.”  Rin began to close the distance between us, her hips swaying seductively.  “All the vials are different, you understand.  No repeats.  And the one I drew?  Was already the ‘just a few inches’ one.  You’re going to shrink…mmm, kind of a lot?  The only question is…how MUCH.  Maybe we’ll end up the same size.  Which would be a HUGE improvement over where the evening started.  But to be honest, I’m hoping for WAY more.”

“How much is ‘way more?’” I asked, my voice cracking.

“You’ll see.”  Rin reached up, grabbed me by the collar, and tugged.  It almost seemed as if she was pulling me down, forcing me smaller.  “See, you’re obviously the kind of guy who gets off on the whole tiny-girl, shrinking violet act.  And that’s fine.  It’s kind of ME, after all.  But ever since we met, I’ve been DYING to turn it around on you.” 

Rin watched as I shrank toward her, clearly loving every second of this.  At just the right moment, she rose onto her tip toes, caught my lips with hers, held me this way.  Her tongue teased against me, forced its way into my mouth as she grew against me.  She kissed me this way until we were the same size.  Then she paused for a moment, looking at me expectedly.  When I continued to dwindle still smaller, at last forced to look UP at her, she nodded smugly.  “Good.”  She went back to kissing me, a little more aggressively now.  She kept at it for a long, long time, as things became increasingly one-sided.

She paused a second time, after some nameless interval had passed, and this time I finally DID stop shrinking.  With a little sigh of disappointment, Rin released me.  She let me step back, survey my surroundings.  I stumbled, nearly tripping over my chinos – they’d fallen to pool around my ankles during that marathon kiss.  I hadn’t even noticed.  Thankfully my button-up was still protecting my modesty, but the way the garment hung all the way to my knees was kind of humiliating. 

Rin watched me take in the giant room around me, with a domineering sort of expression I hadn’t thought the submissive girl capable of making.  The top of my head came no higher than her collar bone, putting her in the running for the tallest woman I’d ever seen in real life.  No, that wasn’t true, I reminded myself.  At this moment, Rin wasn’t much more than four feet tall.  It was just that, well…I was quite a bit shorter.

She stood there, hands on her hips.  “Take your time.  Drink it all in, cutie.  God knows I am.  Do you have any idea how long it’s been since I got to have fun with someone SHORTER than me?  I just have the WORST luck at this game, I mean you have NO idea.”  Without warning she caught me by the shoulders, pushed me, made me walk backward deeper into the kitchen.  “So I fully intend to enjoy myself.  You don’t mind, do you?”

I shook my head.

“Of course you don’t.”  Rin kept pushing me until I felt my back press against the cupboard.   The tiny giantess took the hem of my shirt between her fingers, lifted slightly, waited for me to nod, then slowly drew it over my head.  She cast it behind her with a little flourish.  “Well well well, what have we HERE?” she growled.  She took my hands, made me lift them over my head, turned me like a ballerina so she could inspect me from every angle.  I was clearly being objectified, and while it was demeaning, I couldn’t deny it was a huge turn-on.  “Not bad Alex.  Not too bad at all.  I can see ONE little guy who clearly doesn’t skip leg day.  I mean I thought you were cute before, but DAMN, this is just an adorable size for you.  And such a pretty little cock too.”  With a chuckle, she reached toward my rock-hard manhood.  It gave a gentle twitch in anticipation of her touch, and I gasped as she gave it one, gentle stroke.  Rin cooed appreciatively.

“So here’s what’s going to happen little guy.  In just a minute, I think I’m going to take you some place a little more private.  To…mmm…get a closer look at you.  But before we do THAT, I made you a promise, didn’t I?”

“W-what are you talking about?” I asked, my voice incredibly high-pitched even to my own ears.

Rin smirked.  “Before you took your turn, you asked if you could take these off.”  She booped me on the nose, then drew her fingertip slowly down her own body, until it pointed to the fly of her oversized jeans.  “So you could touch me.  Down here.  Do you still want to do that, shortie?”

The strangeness of the situation made me hesitate, especially considering Rin’s sudden and dramatic shift of personality.  But who was I kidding?  “Yes please.”

She actually laughed.  “So polite!  Now, I’d offer to recreate things just as they were.”  Rin placed one enormous hand teasingly on my thigh, and winked.  “But I’m guessing you DON’T want me sitting in your lap again right now.”

I swallowed, and looked her up and down.  She was big, sure.  But not THAT big.  Maybe it was the urge not to be shown up COMPLETELY – masculine pride and all that.  But also, I was kind of curiosity to see just how much she outweighed me, if I could handle her after shrinking so much smaller.  “N-no.  Actually, you can sit in my lap again.”

She raised her eyebrows in an ‘oh really’ sort of way.

“Probably just for a minute though.  And stop if I say?”

“Of course.”  Rin made a motion with her hand for me to sit down.  But first thing was first.  I tugged on her jeans, not bothering with the button.  They resisted just a little, but they were made for someone quite a bit larger than she was at the moment.  She exhaled softly, a hint of that old submissive cast coming to her eyes – but just for an instant.  I took some small measure of satisfaction in reminding both of us that SHE was tiny, too.  Her panties clung awkwardly to her thighs at an odd, loose angle, but the first time she moved they slipped to the floor as well. 

I took a moment to appreciate my handiwork.  Rin was slim and petite (I mean, relatively so,) with a flat little tummy.  Her sex was smooth, smelling faintly of shaving cream, as if she’d been anticipating that the evening might go well.  From other, perhaps more subtle signs, it was clear she was enjoying herself just as much as I was.

I sat down on top of my discarded shirt, and stared up at the goddess before me.  From this perspective, Rin seemed to stretch all the way to the ceiling.  The wicked grin on her face as she stared down at me suggested that she was imagining what might have happened if I’d drawn a much stronger shrinking potion.  She sunk her fingers into my hair, tugging gently, letting my lips brush intimately against her thigh.  Then slowly, she lowered herself into my lap.

She was heavy – extremely so – but it wasn’t beyond my ability to enjoy the sensation.  It also helped that she kept some of her weight on her hands, so she could grind her giant posterior against me.  I moaned, and wrapped my arms around her the best I could.  Both my hands stroked along her inner thighs, and I sat up straighter until I could reach that soft, warm place where her legs came together.  She sighed, resting more of her weight against me as she relaxed into the stimulation.  Gritting my teeth with the effort, I went to work trying to please her.

It wasn’t hard.  We were both incredibly riled up by this point.  From the first moment I touched her I could tell how soaking wet all the teasing had made her, how pent up she must’ve been.  There are advantages to being tiny, I was discovering.  The places my fingers could reach.  The precision with which I could touch all her most sensitive areas.  I felt Rin’s body vibrating against me as she moaned.  She began to thrust herself back and forth against me as her cries grew louder, as she allowed herself to become lost in the moment.  There was pain, but not much of it, and I was happy to endured it for her. 

It always takes time, with a new partner, to learn all their sounds, the ways they let you know if you’re on the right track, how they indicate they’re getting close.  So it’s only a guess when I say that Rin was about ten seconds from cumming, when her roommate showed up.  We both heard the key crunch into the back door, not five feet away from where we were tangled up on the floor.  We froze like frightened rabbits, neither of us sure how to extract ourselves in time to escape.   When the door swung open a few seconds later, neither of us had moved an inch.