"It itches? Back there feels... itchy." she thought.

Kaede Shimomura was taking her little daughter to school that morning. Just as she had gone to put on her shoes she noticed a peculiar feeling. Underneath her underwear, inside her delicates down below, she felt an itching sensation. As inappropriate as it was, the disturbance was centered directly at her... backdoor.

As she bent over to put on her first shoe Kaede glanced around her shoulder. Underneath the apron she was wearing was her sky blue dress. It rested cleanly over her generous backside, and it didn't seem to be bunching up or anything. Her ample buttocks had spread apart once she bent over, the fabric sliding smoothly between them. Nothing seemed to be wrong. Kaede knew she had a large set of child-bearing hips, and occasionally she would bump into things with it, but there wasn't anything behind her that she could have accidentally touched. She made a frowning face. Even though it looked fine, there was something tickling her back there for sure.

Her daughter Sakura, meanwhile, was watching the whole thing play out. She knew exactly what was bothering her mother and she was the reason behind it. See, Sakura had the uncanny ability to teleport things and resize them, no matter how big. This morning she decided to add something extra special to Kaede's motherly panties, just for the sake of it. Keeping a curious poker face, Sakura watched her mom, thinking about her huge behind as it bent over, wondering how it must seem to them...

----

Their world had been broken up into jagged islands, separated almost by the continents themselves. The terrain was laid out sporadically, about a dozen flat landscapes that could be identified by their distinct mountains and multitude of lakes were now floating in the air, as if by magic. The distance between these islands was immense, some multiple lengths of the planet apart, hardly possible to make contact with again. It was a catastrophe unlike the world had ever scene. 

But that wasn't the worst of it. No, the real danger was what happened to be surrounding the former planet. The islands were floating over a giant chasm, a massive curved pit. Calling it massive was putting it lightly, this huge pit was so big it was barely at the scale most humans could comprehend. The dooming circle had an enormous circumference, nearly comparable to the distance between the Earth and the Moon. Its outer edge was made up of round lumps and huge crevices, growing smaller and closer together as the trailed down to the large center. In the middle of the pit it was dark and desolate but the folded lines of material pinched together in what only could be a giant hole. None of the microbe-sized people would have believed it, but was true: their world was suspended over a giant asshole. 

Thanks to Sakura's little prank, an entire planet was broken up and trapped inside her curvaceous mother's ass crack. The civilians started to panic from the sudden change of atmosphere. Their midday blue sky was gone, and instead replaced with a dark, brown-tinted night. The change was instantaneous and could be felt across their entire world. Almost just as quickly came the odor. A noxious heavy stench blanketed the floating islands of land, covering their towns and cities. It was misty and smelled like old waste, strong enough to make people buckle over and some outright collapse. The steamy scent was so thick that it rolled over the countries like a giant smelly fog, reducing visibility.

With the smell came the abrupt rise in temperature. Suddenly everything became a roaring furnace of heat, where just being outdoors felt like walking in the middle of the desert. Sweltering waves permeated through every city, roasting its tiny residents. The sheer warmth emanating from Kaede's asshole was boiling the little islands inside her panties, as if they were inside an giant damp oven. Moisture stuck to every tiny glass surface and tall tower, collecting from the intense humidity. The smell reeked of sweat and lingering fecal matter, the awful stench of the grown woman's asshole had spread across the entire shrunken world without her even knowing.

The sight of her giant mature asshole was incredible. It was big enough to swallow the floating islands with ease, if it ever opened to expel waste it would mean the end of all life. Each wrinkle was colossal, the puffy bands of folded skin were bigger than any of the hovering masses of land. A few unfortunate continents had ended up wedged between the wrinkles, doomed to even more intense heat and rotten smell. Crops died out, and people choked to death on the horrible stench spreading from the hot grueling anal wrinkles. They had no idea that the awful walls of nature that were destroying their lives were actually the tiny ass crevices of a giant woman. 

Even further beyond the wrinkles expanded far and wide, dwarfing the tiny fractions of land. The bands of skin became fat and puffy, rounding into massive walls of flesh that stood looming overhead the microscopic population. A wispy mess of ass hair stretched above the sky, curving in a multitude of directions. The unkempt hair, normally considered thin, was thick and sturdy enough that a just single strand could slice through a floating island like it was butter. The giant continent would be blown to dust and the people left to fall into the abyss below.

Eventually Kaede's body became aware of the small earthen land masses that were wedged into her sensitive anal folds. The minuscule islands were itching her skin, and making her asshole tickle. In response the giant anus twitched, only a small amount, but cataclysmic to the millions of people living alongside it. The huge hulking wrinkles slammed inwards, crashing into any islands that were unfortunate enough to be near the outer edge. The floating fractions of land were utterly annihilated by her folds, shattered into bits just from a single contraction of Kaede's hole. Tall mountains and skyscrapers rained down into her orifice like grains of sand, indistinguishable from the actual dirt and grime that had collected in her crevices. With just a single twitch her asshole had just wiped out half of the floating islands, and she was completely unaware of it.

As the plump wrinkles started to retract again, a booming guttural sound rumbled underneath them. Deep inside Kaede's motherly ass a huge payload of poisonous gas had collected within her large intestine. The hot murky fart had reached the other side of her backdoor and was almost ready to come out. Loud organic groans shook the floating islands like an earthquake, causing them to wobble and teeter. From all around them the circle of fleshy walls rose upwards, looming higher and higher as the asshole bulged outwards. The fat wrinkles became engorged and tight as they held back the swirling disaster of female gas. There was nothing the tiny people could do but panic, no way to stop the woman's gastronomic phenomenon from happening.

The few hundred thousand kilometers-wide anus widened and released the apocalyptic fart that was stored inside Kaede's large intestine. Her asshole roared violently, making a loud thunderous sound as the hot gas was expelled from her titanic body. The tiny people didn't even have a moment to smell the repulsive eggy scent, the fart had destroyed them in an instant. All the remaining islands were caught up in the stream of gas as it gushed out, in less than a second the giant fart had blown them into little flecks of dust. Just from the shockwaves of this massive woman's fart, an entire civilization had been eradicated. The microscopic pieces scattered as the rest of her gas burst forth, shooting a vast amount of yellow coloured air from deep inside her bowels.

After only a few noisy seconds the fart ended. The vulgar sound being produced by the humongous anus trailed down into silence and the hole closed back up. The remains of the small islands were nowhere to been seen, they had been completely vaporized. Only the raunchy stench of the woman's fart was left over, making her asshole and panties smell terrible. The billions of lives that had just been obliterated went completely unnoticed by the woman, with one bodily function she had ended their existence.

----

PPPPPSSSSSSSSSSHHHH!!

A small fart slipped out of Kaede's butthole. It wasn't particularly loud, but it felt hot and stinky under her dress. She hoped her daughter hadn't heard it, that would have been embarrassing. The gross release didn't last too long, before Kaede knew it, it was over. She let out a sigh of relief, relieving a little bit of pressure made her body feel good.

As the grown woman finished putting on her shoes she noticed that itching in her backdoor had gone away. Whatever it was, a stray bit of lint or whatever, the fart had seemed to clear it out. Her round butt wobbled as she stood up and began to walk forward, free from the ticklish feeling that had been bugging her. As she opened the front door to leave she called to her daughter, making sure Sakura was right behind her.

The little girl put on her shoes and followed suit. As she left, she caught the wafting scent her mom had left behind. It was faint, but it was definitely the smell of Kaede's gas. Sakura smirked to herself, knowing what must have happened to the tiny broken up planet she placed in her mom's huge butt. That smell meant their complete destruction, nothing could survive a blast from a booty that big. She caught up with her mom and walked to school, content with just imagining the catastrophe she had caused.


[Based off: https://e-hentai.org/s/2f9ea9eb02/794992-112 Hopefully the link still works!]