You didn't have any more time to waste. You had to run to the back of the chair, bolt there as fast as you could before your gigantic senpai squashed your tiny body like a bug. Her glorious panty-clad ass was coming down quick, the white fabric sky growing darker as its shadow fell on top of you. If you could just make it to the back of her chair in time you'd be in the safe zone, but it wasn't meant to be. Your tiny legs could only carry you so far, and even after hauling ass as fast as you could you only managed to move your position a few centimeters. At the last moment you spun around, to see your senpai's heavenly butt about to crush you. This was it-!!

----

Matsudo's skirt fluttered as she sat, drifting naturally over the edge of the chair. She was usually the kind of girl to tuck her skirt under her bum when she sat down, unless she was preoccupied with her experiments. Totally engrossed with entering the new data into the computer, her eyes were locked on the screen.

"Okay if I enter the variables right here..."

Her fingers clacked away on the keyboard. A few more seconds went by and she clicked her tongue again, disgruntled that her calculations had still yet to bear fruit. Why wasn't it working for her? She was going to keep at it until she figured it out.

----

SLAAMMM!!

The sound of your senpai simply sitting was an earsplitting affair. It was as if an entire skyscraper had toppled over, shaking the very foundation you had been standing on. You gritted your teeth, waiting for your sad, sudden, and pointless death, but by some miracle you had survived. The giant crushing force of you upperclassman's ass was flattening you into the chair, but you were still very much alive

"I... lived? I made it! I... ... ack! Senpai...! Your ass...! It's so heavy!"

The whole weight of her backside was bearing down on you. Not just that, but the upper body it was supporting too. You had been incredibly lucky, instead of being crushed into a fine red paste you managed to find yourself nestled in the small crevice between her two cheeks. It was the only spot that wasn't pressing flat into the chair, and offered you a tiny bit of breathing room. If she had sat even an inch from where she landed, you'd have been dead for sure. That said, the space between her massive globes was cramped as hell and the ever-present weight of her buttocks was barely pressing down on you to a non-lethal degree. It was hard to move your arms and legs and your chest definitely couldn't budge. Your back was to the chair meaning the front side of your face was being smothered by the weight of her ass.

You couldn't believe how big it was. It was a hard thing to wrap your head around, now that it was right on top of you. Matsudo-senpai had always had a small slender frame, she wasn't exactly well endowed or curvaceous, but she still had a wiggle to when she walked. Sometimes you would sneak a peak at her skirt, watch how it danced as she trotted properly down the school hallways. Daydreaming of how her bum looked under that skirt, you had no idea it would ever become this gargantuan. Her ass was huge and daunting, dwarfing your tiny body under it's volume. Just by it pressing against you, you felt a sense of how large and solid the rest of it really was. It felt like if you put your hand against the outer wall a building and pushed, the utter size of it was immovable. Her ass could easily have crushed the entire school with these proportions and leave it as a pile of dust when it rose back up.

Magnificent size aside, your female friends weight wasn't the only thing right now that was smothering you. A hot sultry blanket of smells were emanating from her ass crack, covering you in her scent and her warmth. It was amazing, the smell of her panties was so rich with feminine musk and pheromones that it made your head spin. You could smell the strong tangy odor of her crotch, the puffy mound that was just inches away from you let out a sweet sensual scent and it was driving your hormones wild. At the same time her ass and its dripping sweat were almost completely overwhelming their own fragrance. Your tiny lungs filled with the hot stuffy smell that came from between her butt cheeks. It was thick and heavy, concentrated with the earthy odors that had gathered inside her crack all day. The president was a clean girl, but to keep her butt from secreting sweat or other smells throughout the day was an impossible task.

The plentiful aroma soaked into your body, making you feel muggy and slow. Just the heat dripping inside her cheeks was exhausting you, and your sweat started to absorb into the giant panties and mix with hers. You were thrilled to smell such a private stench, to experience an intimate odor of hers without her knowing, but after a minute that thrill went away. The smell had begun to get to be too much for you and it wasn't going away, in fact it was getting hotter and stuffier as time went on. You were starting to drown in the heavy alluring musk of her ass, if this kept on for too long the lack of oxygen would be dangerous.

This was bad. It was either you found a way to escape from under her giant butt soon, or you might suffocate. Struggling wouldn't do you any good, her ass was too heavy to push away, even if you had a hundred copies of yourself. That, and exerting too much force would only waste the little air you had. Your only choice would be to wait this out, maybe she was only going to sit down for a few minutes...

...

A few minutes turned into twenty, and the president's gigantic ass was still sitting in its spot. Sure, she would shift and move around every now and then (causing you a great deal of crushing pain) but never once did her ass lift from the chair. She was still stuck the computer, typing away and working diligently on her calculations. It could be hours before she got up, time you didn't have. You were drenched in sweat at this point, gasping sharp breaths that were laced with her potent smells. It wasn't looking good, but it was about to get a whole lot worse.

It came suddenly. A harsh booming noise groaned up above, from somewhere deep within the schoolgirl's body. It was fierce and bellowing, so much so that it was hard to distinguish. The muffled roars echoed on for several seconds, sounding akin to ship's hull moaning against the ocean's waves. You had to brace yourself as the shockwaves came down to Matusdo senpai's ass, the vibrations were so large that they rumbled into the seat like an earthquake. The chair trembled beneath your stuffy prison, causing your body to shake directly against the sweltering panties. The frightening noise trailed off, leaving you to guess what had happened. Your answer came with senpai's mutterings.

"Ugh, I think something I ate's not sitting well with me..."

Her words echoed through her body almost as loudly as the previous noise did. You heard what she said, slightly muffled, but audible enough to get the terrifying message.

"No way... She couldn't actually have to...! There's no way! Senpai may be a bit odd but she's still a girl, she wouldn't actually do that right in the middle of the lab, would she?"

To your horror the groans grew louder, rumbling through the seat a second time. A massive load of pressurized air was gurgling through the giantesses' intestines, making its way lower and lower until... it would eventually come out as a fart. Her gargantuan body, the one that overpowered you by just sitting down, was preparing a release of monstrous proportions. If Senpai casually let a fart rip out her ass right now it would surely mean the death of you. The smell alone would be on a whole other level compared to the grueling fumes you were currently choking on. Even besides that, the impact was probably enough to kill you outright.

"Why..." you whined.

You knew why though. A memory flashed through your mind, of earlier that day. You had given your beloved senpai some chocolates as a treat, something you had hoped to make her smile. It was only until after she ate them with her usual demeanor that you saw the printing on the wrapper. The expiry date was for a week ago... and several years before that! The age-old chocolate must have been the cause of her body's discomfort, making her stomach churn and bubble angrily. Your gift had backfired in the worst way possible, with you on the literal tail end of it!

There was nothing you could do to stop what was about to happen. Her body was going to expel all this built-up pressure whether you liked it or not. Senpai's rumbling ass was now a force of nature, a great storm coming to tear you apart. Her cheeks had you pinned and you could barely move, escape was practically impossible at this point. You had to do something though! Before it was too late!

You knew that if you tried to squirm your way free it would get you nowhere. Even if you could somehow pry this girl's insanely heavy ass cheeks off of the seat and slip your way through her butt crack to freedom, there was no way you could make it in time. Matsudo-senpai normally had a pretty modest butt, but at this level it was too massive to even dream about escaping from. The ticking time bomb that was her fart would decimate you before you managed to crawl more than a few inches of space underneath her beautiful curved rear.

That left you with only one option. If you couldn't stop her bodily functions and you couldn't escape, you had to get her to move. Surely if you punched and kicked with all your strength, she would notice a faint tickle coming from under her ass, right? Then she would get up and realize she had been sitting on you all this time. Most likely she would be mad at you for ending up in such a predicament, but that didn't matter right now, this was an emergency! If you were lucky, maybe you'd even get to see her face as she lets her fart accidentally slip out, the rare sight of your crush blushing in embarrassment from letting out such a disgusting smell. You wanted to see that expression, but first you had to get her to move.

You flailed wildly, using what little space you had to punch at her panty-clad ass cheeks. It was hard enough to move your arms, the low ceiling of butt flesh didn't allow much room to wind up. Kicking was also difficult, your legs were practically pinned to the seat, so all you could do were pathetic little jabs with your feet. You were dripping wet, soaked in a mixture of sweat and humid ass moisture. The wafting smells made your head feel heavy, but you couldn't stop yourself. Again and again you pounded at her giant buttocks, slamming your limbs as hard as you could against the doughy wall. Your chest ached from the lack of clean air, but regardless you screamed as loud as you could.

"SENPAI! I'M DOWN HERE! HELP ME, PLEASE!!" your tiny voice called out.

You had hoped that maybe through the thick layers of fat and flesh she would hear you, or at least feel your voice vibrating at little. Tired, you stopped your assault, letting you arms and legs rest as you waited for her response. The seconds ticked by agonizingly slow... but there was nothing. Senpai's ass wouldn't budge, and she wasn't getting up. The truth was she didn't feel anything from your desperate attack, her monolithic ass was so huge that your minuscule flails hadn't even registered as an annoyance. Your heart sank into your chest as you realized this, you were completely screwed.

Another resounding groan bellowed from above you. The sound was far louder now than it had ever been before, her ass was nearly ready to let it out. You could feel how close it was, gurgling inside the giant beast that was sitting on you. Your heartbeat pounded faster and faster and you started to hyperventilate. Her stuffy female scent stuck to the back of your throat as you panicked. There was nothing left that you could do to save yourself. Huge rumbles shook from inside the girl, pounding your eardrums. At long last you felt it, her muscles tensing up as the fart reached her backdoor. Her gorgeous anus, hidden between her ass cheeks had started to pucker...

The President felt a bubble of pressure stirring inside her rectum. The discomfort she had felt in her guts earlier, whatever if was, was ready to come out in the form of gas. Nonchalantly she pushed with her butt muscles, treating the whole ordeal as nothing but a minor distraction to her work.

"Nnggh..."

The force and heat of her fart was disastrous. You felt like you were lying directly underneath a rocket ship as it started to take off, face to face with the blaring explosion. The sound hit you like a wall, bearing down on your tiny form and crushing it. On the outside the president's fart was a normal trumpeting bout of flatulence, but to you the sound was so huge, so astronomically big that it broke your eardrums immediately. Mighty bursts of air pummeled through her mountainous cheeks, decimating you underneath. It seemed like you were unfortunately close to the epicenter of the blast, in a spot directly under her sputtering butthole. The hot murky fumes billowing downwards turned the seat into a superheated nightmare, a fiery miasma of atrocious stream.

You coughed violently in the midst of the fart storm, hacking up thick rancid air only to have more forced inside your lungs. Your eyes watered as you wretched, you spit out wads of foul moisture while the girl above casually emptied the pressure from her bowels. The smell was ungodly awful, it had been fermenting inside her massive digestive system for hours and now reeked of raw shit. The stifling gaseous stench invaded every one of your orifices, treating your respiratory system to the hot burning taste of her colon. No matter how much you coughed it wasn't enough, your body would never be clean again from the awful stain of her farts. The potent smell poisoned you from within, clogging your lungs all the way until you couldn't breathe anymore.

The grueling fart eventually trailed off, leaving Matsudo senpai's ass surrounded by a cloud of its own wafting stink. For the next several minutes the underside of her panties were hell on Earth, a foul murky hot zone of leftover gases. Your body was trapped in a remaining pocket of shit fumes, unable to move and unable to suck in any oxygen. Slowly you felt your consciousness start to fade and the world becoming darker around you. The pain of being blasted at such a close range had made you body go numb, your bones had shattered from the force of her fart, broken like tiny twigs inside of you. Despite all this, you felt oddly calm.

Maybe it was the stench of her fart affecting your brain or maybe you had finally lost it. You were slowly dying as a result of senpai's fart, but you felt at peace. You would have never thought such a thing to be possible, that your existence would end just because a girl passed gas, but it was actually happening. It was pathetic, miserable even. Your sad excuse of a life was being extinguished because of something like this. You wondered what kind of face senpai made when she farted, if it was cute or if she blushed a little. Just thinking about her made you feel not so bad, at the very least if you were going to die from a fart, you'd want it to be hers...

Even with the muggy heat dripping around you, you started to feel cold.

"At least it was from one of hers..." you thought again

"Sen... ...

...pai..."

...

President Matsudo sat in her chair unsuspecting, when she caught a whiff of her own deed. She wrinkled her nose at the leftover gas, making an unpleasant face.

"Ugh, it stinks" she said.

Sodachi Taiyou...
enclosed and trapped within the meat...
of President Matsudo's gigantic ass,
had his bones and innards violently ravaged...
when she released a massive fart on top of him.

 As a result of the internal injuries, the shock, and on top to that...
the resulting atmosphere of atrocious and noxious gases...
he suffocated, dying of asphyxiation.

 https://giantessbooru.com/_images/a0e0dae2a79a6a8d9b1113b864522bd2/185060.jpg