“Okay so, like, question.”

“Don’t worry, everything will be explained shortly.”

“Why are you naked?”

“I’m glad you asked that!” Prinrin was not, technically speaking, actually naked. But she was wearing significantly less clothing than she would typically have on while at work. And, really, a bra and panties was basically semantically identical to being naked. Considering that they were literally in Prinrin’s office at the moment, and that at literally any second an investor or executive or intern could just sort of bumble their way in meant that there was an inherent risk to wearing this little clothing. “The answer is that this is actually not ordinary underwear!”

“It looks ordinary,” Izzy said, electing to play along for now. She was already certain that it wasn’t normal lingerie – she didn’t need to be told that. Prinrin wouldn’t have specifically asked her to stop by her office just to show off new lingerie. That was just plain out of character. There had to be something out of the ordinary about them. But it was more fun to follow the unspoken script. Izzy played the role of the investor to Prinrin’s inventor, asking the obvious questions so that the goblin could have a low pressure dry-run. Were it Izzy showing off some cool new invention, she was certain Prinrin would have returned the favour.

Though on the other hand, it did look ordinary. Unusually ordinary, even. No frills, no lace. The bra in particular was plain, beige, and utilitarian – a far cry from what Izzy’d have expected from the situation. “It’s just a prototype, of course. Once I’m sure it does what it’s supposed to we can start fancying up the design for the consumer.”

“Okay, a prototype of what.”

“You’ll see~” Prinrin said, heading over to her workbench.

“You should probably be more straightforward. In my experience, investors tend to get, like, suuuuuper pissy when you try to be coy about what you’re selling, yanno?”

“Enh, fair point. But you’re not an investor.”

Izzy rolled her eyes. “Okay, yeah, fair, but I’d still like to know what it is I’m looking at.”

“Gimme a sec,” Prinrin replied, grabbing a small object. It was vaguely cylindrical, shaped almost like an inhaler. Izzy immediately recognized it as a nanogel injector. Standard equipment for basically any kind of tinkering – or at least the kind of tinkering that Prinrin and Izzy both were wont to do. “The short answer is that this is a Bra of Holding. No matter how busty you get, it can handle it.”

“Oooh, that sounds fun!”

“Well... In theory, at least,” Prinrin admitted, a little bit sheepishly. “It’s held up well enough so far, but I’ve not gotten around to doing any proper stress testing. Which is what you’re here for, by the way.”

“Okay, sure, I’m up for makin’ your breasts absurdly huge.” It wouldn’t have been the first time one of them had acted as a spotter while the other underwent absurd breast expansion shenanigans. Really, it was mostly Prinrin who did the breast expansion stuff. Not that Izzy never indulged in making her boobs bigger, of course, but the key detail was that Izzy’s boobs were already enormous by default. Easily twice the size of her head, where Prinrin was only just beyond the point where you could reasonably measure it with standard cup sizes. Factoring in whatever mechanisms the bra had in place, they currently looked to be around D cups, maybe a bit bigger. There was probably an element of jealousy there – well, okay, no, not probably. There was definitely an element of jealousy there. It went mostly unspoken because that’d be weird, but it was undeniably there. It probably didn’t help that it was kind of fun to rub it in? But in the end that was just good natured ribbing, and she was pretty sure that Prinrin understood there was no malice behind it and anyway it’s not like her natural bustline had any correlation with how big they typically were. After all, if you gave a goblin constant free access to boob-boosting nanobots she would absolutely use them on the regular, or at least Prinrin would.

The point, getting away from that line of thought and back to the subject at hand, was that it was almost always a bad idea to really let loose with the boob biggening without having someone whose boobs aren’t getting biggened close at hand. You could never guarantee that the boob biggening wouldn’t get out of control, and after a certain point mobility would inevitably become an issue. Basic safety, like having a spotter while lifting weights. Which, unfortunately, meant that Izzy was probably not going to get any bigger today. A bit of a shame, but she wasn’t too bothered by it considering that she also had constant free access to boob-boosting nanobots.

“You ready?” Prinrin asked, and Izzy nodded in response. “Okay, going to inject myself now. Let’s start slow and work our way up to ridiculous.”

“Sounds like a plan!” Were it up to Izzy, she’d probably have just immediately jumped into the deep end, as it were. But, well, for the purposes of stress testing it was probably best to move in relatively small increments, to more easily keep track of where any potential points of failure might be.

It was just kinda boring, is all.

“Initiating phase one now.” Prinrin had slipped into cold clinical analysis mode, which was understandable but also boring. She pressed the injector firmly against some visible green breastflesh and, after a moment, there was a soft hiss that signified the first round of nanites had been injected. The only thing left to do now was wait.

And wait.

“I feel like something shoulda happened by now.”

“In addition to being capable of containing breasts of any size, the Hammerspace Bra also conceals your size! Perfect for allowing exceptional folks to fit through doorways.” Prinrin smirked smugly, putting her hands on her hips to complete the look.“It might not look like it, but my breasts have definitely gotten bigger!”

“Oh. Cool, but kinda lame.”

“Oh ye of little faith, thinking I’d make you sit around watching my boobs not get bigger.”

“That’s kinda been all we’ve done so far!”

“Well, you see, the initial inspiration for this whole thing was for girls with hyper tits to be able to function in day to day life without their boobs getting in the way. Buuuuuuut then I thought that it’d probably be difficult to take it off and put it on if it was sized for normal boobs and anyway what’s the fun of having hyper boobs if you can’t show ‘em off?” She once again grabbed something off of her workbench. A big hunk of metal and plastic with a dial on the side. “Obviously, like the bra, the final version will be prettied up and probably a lot more compact, but the functionality is in place. The point is that the compression effect is manually variable. Right now it’s at the maximum strength, annnnnd...” She sharply twisted the knob counterclockwise as far as it would go.

There was an audible fwumph as Prinrin’s breasts abruptly went from large D cups to rivalling Izzy’s. “This is what it looks like with the compression effect as low as it goes.”

“Ah hell yeah, now we’re talking!”

Prinrin smirked. “I had a feeling you’d like this feature.” Her smirk widened to a big ol’ grin, like a kid in a candy store. She twisted the dial back and forth as far as it would go in both directions several times, the abrupt changes in size resulting in some nice jiggling, especially when they were at their maximum size. The goblin giggled before turning the compression back to maximum and composing herself. “Sorry, had to do that.”

“Like, it’s fine,” Izzy said with a shrug and a dismissive wave. “I’d have been mad if you didn’t. We can pretend it’s part of the tests or something.”

“Hell yeah.” Prinrin put the dial back on her workbench and picked up another nanogel injector. “That’s phase one of stress testing passed with flying colours. The bra can handle mild hyper at maximum compression and it can handle abrupt changes in compression at this scale. Let’s escalate.”

“Alright! Now you’re speaking my language!”

“Well, not yet. Gotta escalate slowly or it’ll be difficult to tell where the point of failure is. Hopefully nowhere.”

“Oh, boo.”

Prinrin elected to ignore the peanut gallery in this particular instance. “Right. Beginning testing phase two.” She repeated the process; press nanogel injector on some exposed boob, wait a moment for the soft hiss that signified it had done its job, and discard it. She was very familiar with injecting nanomachines to modify her body, and so as a result every step of the way was smooth and practiced. Like before, her breasts didn’t visibly get bigger, though unlike the first time she found herself squirming a bit, her cheeks flushing slightly as she bit her lip. “Okay,” she said, after a moment to recompose herself. “Looks like it can handle this level pretty handily.”

“Like, how big are they?”

“I don’t know. Let’s find out!” Prinrin grabbed the dial and immediately turned it all the way counterclockwise with the same enthusiasm as the last time. “Ack!” she shouted as the sudden massive change in weight threw off her balance and caused her to fall forward. Thankfully, she didn’t fall particularly far, her boobs acting as impromptu cushions. They were well beyond Izzy’s at this point, easily big enough to reach her knees when she was standing. Probably big enough to impact her mobility. “Okay, uh, note to self. Be more careful about that in the future.”

“Want a hand getting up?”

“Nah, I’m good.” Prinrin turned the compression back to maximum, pulling herself back up to her feet. “Just gotta take things a bit slower next time. Especially since they’re gonna be bigger.”

“Don’t forget to do the thing!”

“Right, right, it’s an important part of the testing and not just a one-time excuse to be silly,” Prinrin replied, rolling her eyes a bit. Still, she repeated the ‘test’, turning the dial back and forth between maximum and minimum settings several times in quick succession. This time, seeing it coming, she managed to keep her balance (though the resultant jiggling did leave her a bit wobbly on her feet). “Right, that’s phase two done with. On to phase three.”

“Mmmmmaybe take a couple seconds to recover?”

“Mmm, no. Let’s save that for when I get really big. We’ve got a ways to go, so I’m gonna try to go as quickly as I can so we’re not here all day.” Prinrin put the dial back on the table and picked up the next nanogel injector. “Right, phase three.”

“Woo,” Izzy replied, her enthusiasm waning. An unfortunate reality of product testing was that, no matter how lewd the product might be, after a point it would inevitably start to get kinda samey. And samey meant boring. Usually it started to get tired before you even got to the fun bit, which sucked because it meant the fun bit was less fun. It was unavoidable, of course – products had to be tested, and the data from the tests had to be useful, which meant going against all her Mad Scientist instincts and taking things slow and methodical. But that didn’t mean she had to like it.

Though hopefully that wouldn’t be the case this time, because she had something in mind to spice things up. She just had to be patient.

Prinrin followed the same routine as the previous phases. This time the growth was noticeable, if only very slightly. A fraction of a cup size, only visible at all because they were specifically looking for it. Still, minuscule as it was, it prompted a frown from Prinrin. “Hrm. Looks like we’ve hit the point where the compression starts to fail.”

“It’s not too bad.”

“Yeah but we’re only just out of the lower ends of hyper. Definitely gonna hafta shore things up before we go into full production. I’d wanna be at least twice as big as I am now before getting spillover.”

“How big are you, anyway?”

“Let’s see!” Prinrin grabbed the dial, turning it clockwise much slower. In spite of her attempts to take things slower, the vast difference between her current size and her actual size meant that each notch equated to several cups of boobage in awkward spurts. “Ugh, speaking of things to tweak in the final product...” she blushed slightly, fidgeting as her growing tits jostled each other. “Definitely gonna wanna smooth this process out in the final version. It just doesn’t look all that good, you know?”

“I dunno, some people might be into that.” Including, it seemed, Prinrin, given the way she was fidgeting as her breasts jiggled and jostled and grew.

“I guess? I’d still say that more fine control over size has more mass-market appeal, though.”

“Maybe it’d be better if you just did the rest all at once,” Izzy suggested. “Like ripping off a bandage, yanno? Like, we know that the decompression process isn’t smooth enough so, like, at this point it’s prolly better to get it over with.”

“I guess...” Prinrin replied, sounding unconvinced. She turned the dial another notch, shivered as her breasts grew even more, jostling and jiggling against each other.

“At this point you’re basically just teasing yourself.”

“Yeah, okay, you’re right.” She sighed. “I just don’t wanna end up floored again.”

“Like, given how big you got last time, I don’t think you’re gonna be able to avoid bein’ floored again.”

“Mneh, yeah.” Prinrin sighed again, before biting her lips, closing her eyes, and turning the dial the rest of the way.

There was a loud fwoomph, and Prinrin found herself immobilized. They were about twice the size they had been for phase two. Beyond reaching her knees, they reached the ground, even when she was standing up perfectly straight. They also pointedly reached above her by a significant margin. “Ah, yes, this is a bit of a problem.”

“You’ve been bigger before.”

“Yeah but I can’t reach around these to turn the dial.”

“Oh. Duh. Here, lemme help.” Izzy strode over and calmly took the dial.

“Thanks. Just turn it down for now, we can do the whole stress testing thing after I get some fresh air.”

“Nah.”

“Wait hold on what do you mean nah.”

“Well,” Izzy said as she calmly tossed the dial out of one of Prinrin’s office’s windows. “What I mean is that, like, this has been fun and stuff, but it’s gotten kinda boring so I’ve elected to spice things up a bit.”

“Oh.” Prinrin sighed. She probably should have seen this coming – really, she did, she’d just elected to ignore it until it was relevant. Izzy had a longstanding habit of getting bored during product testing and taking ill-advised actions to spice things up a bit. Really, if anything, Prinrin had probably subconsciously been planning on it. Or maybe consciously, she didn’t know at this point. It was somewhat difficult to properly process her thoughts once Izzy rolled her over backwards so her colossal titties were resting on top of her. She honestly didn’t mind the situation, and if anything she was a bit relieved at the change of pace.

Of course, she wasn’t gonna say that. It was much more fun if she put up a token fight.

“Mnph!” was the most she could actually manage – as established, she had an awful lot of green titty directly on top of her.

“Don’t worry, I’ll roll you over eventually probably.”

“MNPH!”

“I’m not gonna let you get suffocated by your own boobs, relax.” Izzy carefully manoeuvring around the massive mounds of green titflesh, making her way to the workbench. “I just wanna see what we’ve got to work with first, is all.”

“Mnph.”

“Like, I told you it’s fine.” She picked up the remaining nanogel injectors one at a time, turning each one over in her hands a few times as she examined their settings. “These are all, like, soooooo small! You’re barely gonna get bigger than you are now at this rate!”

“Mnph.”

“Like, you’re supposed to be stress testing this thing but you’re not gonna even outgrow your office? Come on, you can do better than that.” Izzy carefully and deliberately fiddled with the small dials on the side of one of the injectors, tweaking the settings to her liking.

“Mnph?”

“I figure that we’ve taken things slowly for long enough. Like, I figure what better way to properly stress test this than to go as big as we can without, like, squashing ourselves to death or somethin’.”

“Mnph!!!”

“I said without squashing ourselves to death! Geeze, you worry too much.” She lifted up the nanogel injector, turning to face her still prone friend. “Hold on, I’m gonna roll you back over.”

Prinrin took a deep breath the instant her face was exposed to fresh air – the air inside her cleavage had started to get a bit stale after a bit. Izzy continued rolling her until she was resting on top of her boobs like they were a giant green waterbed. At this point, Prinrin’s boobs were about as tall as Izzy was, maybe a bit taller. Which, apparently, counted as too small? “Don’t go too crazy,” she said. A bit more tersely than was probably called for, but on the other hand there was an awful lot of expensive equipment in her office.

“Hey, when have you known me to go too far?”

“Literally constantly.”

“... Well, yeah, okay, not gonna lie.”

“I can’t exactly stop you from doing whatever but any property damage is coming out of your paycheque.”

“I’ll take it,” Izzy said with a shrug, before firmly pressing the injector into the nearest available patch of breast meat. After a moment there was a dull hiss, and then after another moment there was a low rumbling.

“Izzy, what did you do?” Prinrin said. Her concern was only sort of feigned – she was still playing along, but also her boobs were rumbling.

“Like, I keep telling you it’s gonna be fine. You just need to trust me!”

“Mnn, see, saying stuff like that is exactly why I don’t trust yoooooooou!” Prinrin was interrupted by a sharp spike of arousal as her boobs began to grow. It felt good, of course. Growth almost always did, especially when facilitated by nanobots. That was as much out of necessity as it was a fetishy thing. It turned that without nanobots fiddling with how you process sensations, flesh and bone coming into existence where there used to be nothing kinda hurt! Especially when it did so quickly. Like growing pains but moreso. And so rejiggering the body’s pain response so it interpreted the growth specifically as pleasurable instead of painful came standard with just about every nanogel that would result in any kind of growth. And especially any kind of rapid or substantial or rapid and substantial growth.

Prinrin’s boobs grew both rapidly and substantially. Not a big surprise considering who, exactly, was behind the growth. She writhed on top of the vast expanse of green flesh as the pleasure spiked higher and higher without any real means of release. It wasn’t like she was in a position where she could deal with it herself – her boobs were already too big for her to comfortably reach around them before they started growing. And the bigger she got, the more unfeasible tending to her own needs became. She absolutely wasn’t going to be able to touch more than a fraction of tiddy at a time, and while she could probably get at her crotch it wasn’t very comfortable. And so she just had to settle for writhing in the hopes that it would provide enough stimulation.

It wouldn’t, of course. She had enough experience to know that it’d take a lot more than rubbing her body against itself could provide. That was an inherent problem of immobilizing degrees of hyper – it tended to result in this exact situation.

Which, she supposed, was why it was a good thing that she had an extra pair of hands to help deal with things.

Or at least it should have been. Izzy seemed oddly content to just watch for now. Mildly frustrating but not too surprising. Izzy was just as prone to teasing as she was to diving right the fuck in. Annoying, but she would have to deal with it. It wasn’t like she could really do anything about it either way considering that, again, immobilized by tiddy. For now, Izzy was in control and all Prinrin could do was wait.

And while she waited, she kept right on fuckin’ growing. The rumbling continued, and if anything seemed to get louder and deeper. Her breasts took up more and more space in her office, and as they did she could feel them steamrolling everything and she could feel everything they steamrolled with agonizing detail. Every contour of the faux-wood flooring. Her chest bumping into the table that held the nanogel injectors, knocking it over. Discarded pens and pencils and nanogel injectors that she’d forgotten about. Trash cans. The actual workbench itself – that one was especially bad because it was big. Her boobs swelled and sloshed – sloshed? Sloshed. And there was a telling fullness, too. “Oh my god you didn’t.”

“I absolutely did,” Izzy replied with a manic grin.

“You realize that’s gonna completely fuck up the results, right?”

“Like, how so?”

Prinrin sighed. “It’s like... right now I’ve only accounted for boob size. Nothing else.”

“Ssssso?”

“Oh my god,” Prinrin muttered, pinching the bridge of her nose. “I really shouldn’t have to explain this point by point to you.”

“Like, I mean, at this point it’s kinda too late?”

“Ugh whatever just hurry up and squeeze my tits.”

“Can do!”

It turned out to be easier said than done. Not for a lack of trying, but Prinrin had a lot of tit to squeeze and there was only so much Izzy to do the squeezing. At this point each individual milksack was significantly bigger than she was, and still getting bigger. There were a lot of logistical problems to overcome – giving both tits adequate attention at the same time without getting rolled over by them was going to take some creativity, or at least some climbing. Lucky for Prinrin, then, that Izzy was an industrious person. “Okay, hold on. I’ve got a plan.”

“Oh boy.”

“I’m gonna climb you.”

Prinrin’s immediate instinct was to request that Izzy please not climb her, but she elected to suppress that instinct for now. Unfortunately, sitting on top of Prinrin’s chest was probably both the safest place to be. And, though she didn’t quite want to admit it, she really wasn’t in a position to be choosy. Every second that passed her tits got bigger – and, more pressingly, fuller. This was absolutely not her first lactation rodeo, and she was familiar enough with it to know that eventually she was gonna run out of room and it was gonna start to hurt. She needed her tits squeezed as much as she wanted them squeezed – if not moreso.

Well okay that was a lie she absolutely wanted her tits squeezed more than she needed them squeezed. Not that discomfort and pain wasn’t going to eventually be a problem. But mostly she was just fucking horny and needed some god damn release. “Just get it over with,” she practically moaned more than said.

“Hup!” Izzy clambered her way up on top of Prinrin – which, in and of itself, felt really good. Prinrin had bit her lip quite a few times over the course of the evening, and she didn’t foresee this time being the last. The way Izzy’s body pressed into her titflesh as she climbed up was practically agonizing, and also prompted the first leaking. Prinrin hissed through clenched teeth as the pressure relieved just enough that it actually made things worse. Izzy, for her part, didn’t react to Prinrin’s obvious discomfort, quickly sitting down on top of a boob slightly behind the goblin’s main body. “Okay, like, hold onto your pants ‘cause I’m gonna give you a ride!”

Prinrin would have asked what exactly was meant by that, but Izzy elected to demonstrate immediately. She stood up – which was bad enough, concentrating all her weight into a much smaller area and wobbling unsteadily as she carefully manoeuvred herself around behind Prinrin. The goblin moaned, low and lewd, which quickly transformed into a high pitched scream as Izzy sat down with more force than was really called for, legs splayed out across the curve of her breasts. Of course it resulted in more leakage – she could feel the bra slowly being soaked through beneath her.

Izzy could not feel the bra being soaked through, and even if she could, Prinrin was fairly certain she would not care. “So, like, are the panties important or are they there to just complete the look?”

“It’s all the bra,” Prinrin responded as coherently as she could. “Why do you-”

“Neat. That means I can get away with doing this.” What followed was significantly more unceremonious than was probably called for, and Prinrin honestly wasn’t sure whether she preferred it that way or not. Izzy grabbed the panties and removed them before lifting Prinrin up by the legs and burying her face in gob-crotch.

“Ahn!” was all Prinrin could manage. No words, just a noise that was reduced further into a wordless cry as Izzy squeezed her thighs together. Or at least attempted to, but she didn’t really need to succeed because it was clearly less about her legs and more about Prinrin’s boobs. The oral stimulation was bad enough, but also Izzy had finally managed to squeeze Prinrin’s tits and oh man did it feel fuckin’ good. The relatively tiny trickle of milk turned into a fuckin’ torrent, gallons of the stuff flooding her office, soaking into the nice hardwood flooring and the expensive prototype bra alike. Prinrin really probably should have been incredibly annoyed about that, but found herself having a hard time caring about anything other than how good it felt. The way Izzy’s thighs pressed against her tits, the way her tongue danced in her pussy, rubbing idly against her clit. God, it was almost too much to take. It didn’t help that her boobs were still fucking growing, either. She could feel them starting to press against the walls – which would probably have been worrying were Prinrin not so distracted by finally fuckin’ climaxing.

Of course the flow of milk redoubled as a result – between cumming and also her boobs mashing against the walls of her office, she’d have been more surprised if they didn’t squeeze out more milk as a result. Her hips bucked and writhed in Izzy’s grip as the mantis kept right on eating the goblin out. There were rubbery growth noises, accompanied by low moans and wet squelches and then a loud, sharp snap as the bra finally snapped.

“Fuck!”

“Oh. Well, like, at least now we know the point of failure?”

“No we don’t,” Prinrin grumbled. The bra breaking had acted as something of a reality check, snapping her out of the fog of arousal. “The prototype wasn’t waterproofed. Which I tried to tell you but, like you said, it was a bit too late.”

“Oh.” Izzy blushed sheepishly. “Sorry, that’s my fault.”

“Yes, well, you can make up for it by cleaning up this mess once I shrink back down.”

“Okay.”

“Also you’re paying for the next prototype.”

“... Yeah, okay.”

“Glad we’ve settled that. Now, how long is this gonna last?”

“Like, a few hours. You should be done growing though.”

“Okay,” Prinrin said with a nod. “In that case, stop sitting there and get back to work. My tits are only gonna get fuller and right now it’s your job to empty them.”

“Yes, ma’am!” Izzy replied, immediately diving right back in.

Really, Prinrin probably should have had Izzy grab a nanogel injector to expedite the shrinking process. But, well, she wasn’t entirely out of that state of mind-numbing horny yet, reality checks aside. She might as well take advantage of the whole debacle and enjoy herself a bit.

She did have to admit, though. As much as she was annoyed at the property damage and the ruined prototype, it was at least a hell of a lot more interesting than product testing typically was. More fun, too. And for now, that’d hafta be enough.