"And you're sure this would all be safe?" Jay asked, sitting on the black leather couch of the apartment him and his partner Tina shared.

"I've been promised it's safer than taking a plane let alone that hour-long commute of yours" Tina boldly declared with no real evidence in an attempt to comfort her boyfriend on the safety of the app she'd been excitedly explaining to him for the past hour.

Tina, the 23 year old freshly graduated design student, was more than excited about the new app her friend had showed her last week.  To be more specific, the extremely experimental unreleased app her friend Sam had given her after plenty of begging and only with the promise that she'd treat it like a real beta test and report everything.

Tina had her ideas as to where the app came from, Sam's nerdy, recently hired my a mysterious tech company boyfriend sprang to mind.  But Tina didn't care about that part in the least, she was far more interested in using this app to sate her own curiosity, among other desires, with her boyfriend.

Jay himself was as curious as anyone would be when approached by their partner with an app that can seemingly break the laws of physics and modify human sizes.  The things Tina was talking about doing on the other hand had him hiding a hard on while he pondered the safety of it all.

"I mean if my darling girlfriend wants to do this, who am I to disappoint her" He said with his doubts seemingly assuaged.

"Yay! thank you so much sweetie, I promise you'll love this just as much as I will!" She  bounced up and down like a kid finally about to open a Christmas present they waited all night for.

"So how do we start?" Jay asked as he got up from the couch to see what Tina was fiddling with on her phone.

"The app pairs with anyone within a certain radius so we can start right away!" as she said this Tina handed the phone to Jay and pointed to a few settings.

"This slider will change my size up to the limit I set so feel free to make me as small as it lets you" she said with a wink as she slowly leaned into her boyfriend with her lips by his ear.

"And I can't wait to see how big you get" She whispered into his ear seductively as she began to slowly rub her boyfriend's crotch.

With that encouragement any resistance to the idea Jay may have had left vanished, just as quickly so did 6 inches of Tina's height as he gave into her charms.

For Tina the change was instant and jarring as her already petite 5'6" frame dwindled down to 5' flat, From Tina's perspective her already 6' boyfriend seemingly gained 6 inches of height in the time it took her to blink.

This change was both terrifying and exhilarating at the same time as Tina went from barely looking up to meet her boyfriend's vision to needing to crane her neck to do so, this simple change made her far more excited than she thought she could get as she began to undo Jay's belt.

"Let's see how this guy looks at this size" She giggled to herself as the pants came down and out came Jay's erect 5 and a half inch cock. "Someone's happy to see me shrink isn't he" before he had a chance to respond she had already started to suck his dick with an even tighter set of lips than he was used to.

"Think I can still take this whole thing at this size?" she asked, more as a challenge to herself than anything as the only response she got from Jay was moans of pleasure as she kept going.

On the next pump she took his whole cock in his mouth and struggled greatly with the last inch as she took it into her throat just barely succeeding with the task she set out for herself.

"How about we take this to the bedroom?" Jay barely got out through his moans, "I thought you'd never ask" Tina responded with a devilish smile that boiled with lust.

The two darted towards the bedroom all the while doffing what clothes they had left, a particularly easy task for Tina who was already wearing seemingly oversized clothes.

As the two landed on the bed together Tina rolled on top of Jay and hovered her now bare pussy over his awaiting member, with his hands landing naturally on her hips Jay pulled Tina onto his eager cock.

Shock filled her body as Tina took in this dick, seemingly at a much larger size than she was used to, the pleasure from the insertion set her senses on fire as she craved more.

She began furiously riding up and down Jay's thick member, the pleasure of which blinded her to her partner's subtle use of his phone as she was suddenly shrunk once more, another six inches placing her at 4'6".

The pleasure was out of this world for Jay as the pussy he had been fucking so often recently got incredibly tight to the point he may finish in just a few pumps at this rate.

For Tina this change in size felt like more than she could handle as the cock inside of her grew proportionally larger and now bulged just under stomach with every pump, the pain of taking in such a massive object melted with the pleasure as she continued her efforts albeit while occasionally taking in a little less than the whole member.

Noticing this Jay grabbed his now beyond petite girlfriend by the abdomen and pushed his way deep inside her as she wailed in what he hoped was mostly pleasure, this seemed to completely stun Tina as her eyes glazed over from the action.

Leaning up towards her ear he asked her "Do you want to get smaller for me baby?".

The pleasure had nearly made her pass out but hearing that jolted her awake as Tina couldn't help but imagine the feeling that would follow her shrinking, she gave a timid nod, not completely sure whether she should but indulging all the same.

With that she shrunk again, this time only losing another 3 inches to both her joy and dismay as some part of her wanted to be even smaller while the rest of her mind was busy dealing with the feeling of growth inside her as the already massive cock grew once more for her.

The increased tightening made Jay understand neither he nor Tina would last long at this rate.

Rolling over Tina was now underneath Jay, her seemingly almost 8 foot tall boyfriend, she pondered to herself the specifics of their size for mere moments before the giant before her drove his massive cock into her now barely large enough to contain it pussy.

The pain alone felt like it could knock her out but the overwhelming desire for the pleasure she was feeling right now completely removed any other feelings from her mind, as Jay started his final series of pumps Tina knew what was coming.

Both of them began to moan furiously as all the two could feel or think about was the pleasure they were feeling right now, Jay realizing his estimations from before were useless now began to thrust as fast and deep as he could knowing he wouldn't last another minute like this.

Being on the receiving end of this final series of thrusts made Tina's mind go blank with pleasure as she came furiously from the greatest pleasure she'd ever imagined.

Feeling the spasm of her orgasm Jay finally pulled out and came just as she did, a massive torrent of cum flooding from his cock, underneath him Tina recovered from her orgasm just long enough to see her looming lover deliver far more cum than she thought possible all over her stomach completely soaking her in his juices.

"Fuck me that was more than I expected" the giant known as her boyfriend exclaimed, quickly rushing off to get her a towel to clean up and bathe in the afterglow of that perfect orgasm.

Tina cherished the feeling of being coated for a few minutes before wiping herself off and nuzzling into her massive boyfriend's chest.

"We definitely need to do that again" Tina said with more than a hint of enthusiasm "after the soreness goes away that is" as she began to feel the after effects of what they'd just done.

Worth it she thought to herself before her thoughts were interrupted by a question from Jay "How small could I have made you by the way?" he asked curious as to how far she would have gone.

At this point she'd completely forgotten about the app after everything that happened, "I don't remember what I set as the minimum actually" she realized in the moment, "are you getting curious about this stuff now?" Tina asked, flashing a haughty smile impressed that she'd converted her boyfriend so easily.

"Well I was just thinking it would be a waste not to try it out, you said we were testing it after all"

"In that case take me away darling, I'm curious to know just how small I'll get" although a bit nervous she did want to push things as much as she could.

As he swiped his finger across his phone moving the slider as far left as it could go Jay watched Tina dwindle from her previous height of roughly 4 feet tall down to 3 feet as she crawled further onto his chest, barely even feeling a difference in weight he continued to hold his finger as she continued to shrink.

Tina was in awe watching her boyfriend go from something that resembled a large human to more of a bed sized object, she was amazed at the scale of it all until she realized she was still shrinking.

How far did I set this she began to ponder to herself, she began to worry when she would stop, soon she was no longer laying on Jay's chest but standing in order to be eye level with him.

But it just kept going.

Soon she was staring upwards at the face several times the size of her own body, she couldn't have been more than three inches tall, suddenly the world grew even faster as she realized the shrinking would make her perceive the world as exponentially larger as she got smaller and smaller.

She eventually stopped shrinking at what she estimated to be half an inch, Jay's chest had become a massive field made of alien material, his lower body seemingly spanning miles into the distance, all the while Jay himself seemed to have grown into a distant god peering down on her.

"Wow you're into weirder stuff than I thought babe" The titan began to speak, from Jay's perspective it was barely average volume but to Tina it was a shock wave she could barely understand as she held her own ears to lower the ridiculous volume she was faced with that suddenly erupted from the god's mouth.

In that moment Tina realized her own insignificance, she trembled in fear of course, but also in overwhelming pleasure as she stared up at the man who had nearly deafened her with a few quiet words.

I'm going to really enjoy this app, she thought to herself as she gazed in awe at Jay and the overwhelming landscape he had become while slowly began to bring her hand lower to a part of her body that was already eager for more, realizing they had just scratched the surface.