Nina tenderly caressed Hime's face with a hand, using the other to guide her back against the floor before straddling atop her.  The changing room was stuffy but it had cooled since the school day ended, and the two girl's nipples were markedly stiffened from the chill of the room.  They pulled each other close, locking their legs and resting the jewelry box beside them on the soft floor mat.

Nina pressed her chest against Hime's soft slightly plump belly, savoring the flushed warmth of her skin and tracing a finger up past her navel to swipe a stray drop of pudding that had  dripped down to the underside of her breast.

She brushed her straight bangs aside her face and tenderly traced her tongue over the pudding draped breasts before her. She rolled up the last of the continent-sprinkled sweetness off the stiff pink peak of her nipple and swallowed, staring up lovingly into Hime's eyes as she suckled tenderly on her pert breast.

Hime sighed tenderly at the shared warmth between the two girls, and placed her hand atop Nina's head.  

"I like sharing the world with you Nina, It makes me feel like we're the most important thing in it."

Nina grinned, "Heh- I was wondering if you felt that way too."

Nina lifted herself off of Hime and pressed the open case against the mat before lifting it and revealing a trio of billiard ball sized worlds. The surfaces of these spheres were entirely grey,  their surfaces  entirely covered in urban sprawl.

"The cities are the only interesting part right? Maybe we'll even be able to feel them moving around in em'."

Hime blushed and  nodded. "Yeah- this is the best. What's first?"

Nina dotingly rested her pinky beside one of the planets, measuring up the miniature planets against her smallest finger. The cities she had imagined had the tallest buildings Nina could imagine, but they must have been far less than a millimeter high. To her it looked like a grid of fine gray sand  decorated by grids and webs of highways and canals.

"Come on Hime, give them a good look at you too." Nina giggled, prompting her to lean in and rest a pink nipple beside the planet.

"So cute." Hime chirped.

"Yeah- I wonder if any of them recognize you. " Nina smirked. Hime raised an eyebrow. "Huh?"

"Hehe, nothing. Hey, do something to em'." Nina prompted.

Aoi rolled over in bed, grabbing his phone and checking the time.

"6:23" He muttered. "Where is she? Isn't like her to be so late getting home."

Hime was only ever this slow to leave school if she was studying with friends or if that friend of hers was holding her there all day.

"Geez. Gonna have to heat up dinner for her at this rate. He closed his eyes again and sighed.

A deep thump echoed outside- lightly jiggling the figures and books on his shelf. People up stairs at it again Aoi thought.

The air wafting in from his open window suddenly warmed slightly, and Aoi's nose twitched slightly at its scent., warm and musty like a hot summer evening.

*THUMP*

This time too loud to have come from inside- and heavy enough to knock a few items off his shelves and desk.

"Huh? Not an earthquake is it?" Aoi lazily shifted onto his feet and walked over to the window.

Aoi made it within a few feet of his window when he jolted back briefly, then threw himself forward to grip the windowsill to steady himself.

"Wh-what the hell?" He shouted, gazing up and leaning out the window.

Stretching up higher than any mountain beyond the horizon  was a colossal pink expanse, round and soft and at a size that defied all logic. Tracing the contour of it upwards further it seemed to be just the tip of another immense pink shape-

A nipple, he immediately recognized. As impossible as it was he couldn't deny that the country-sized form was a woman's nipple; and a rather small one at that. His eyes traced up further past the seemingly endless rise of breast until he could comprehend that it belonged to a resting figure that completely stretched away into space. When his eyes reached the figure's face he started and gasped.

"What?!" Is that? No, it can't be- h-how?!" He muttered in disbelief.

Staring down with a tender expression of curiosity and playfulness was Hime.

Hime- who must have been a hundred times the size of the entire world, and indeed was above and outside of its confines.. The distance beyond her form was out of focus, but he could just make out the form of lockers and a door stretching above her and the soft glow of artificial lighting where the sun had once been.

Sprinting away from his window Aoi ran downstairs and into the street- where others in  his neighborhood were doing the same, glancing up in disbelief and shock. A voice called out describing a second visage and sure enough he turned to witness another girl- Hime's friend from school he recognized- staring down with a chillingly indifferent grin.

With a gust of strangely vanilla-scented breath a voice louder than any he had heard before uttered.

"Hey- do something to em'."

Hime lifted her chest away from the planet and rested her back against the bench behind her. With great care she plucked the world up and brought it between her spread legs. The sense of deific scale dawned on her as even her little clitoris poked out towards the planet as if it was a small moon.

Each heartbeat elicited a twitch of the nub, now glossy with perspiration and arousal. Its menacing movements threatened to stab apocalyptically at the surface, which only served to further hasten her heartbeat and breath.

"Go on~" Nina complained, her fingers rubbing at her own slowly dampening labia. 

Hime glanced at her nervously, then down at the planet pinched between her fingers. With deliberate tenderness she brought it just below her clitoris and pressed it until she felt the slightest tingling of the surface against her skin. Despite just how diminutive the surface was she could feel the faint differences in texture between the cities, suburbs, mountains, and valleys.

Letting out a quiet sigh of excitement she brushed the planet upwards, letting her now almost painfully stiff clit scrape across an entire continent and what must have been billions of microscopic buildings and people. 

She hadn't the slightest notion that thanks to Nina's mischievous nature a microscopic simulacrum of her older brother was one of them.

Aoi gasped as he witnessed her nipple recede away from the planet faster than he could imagine. He could see her immense form shift as her fingers flanked both sides of the horizon and lifted the entire world beneath him down between her towering thighs.

The sudden blast of warm air that heralded her approaching crotch was stifling; the stuffy scent of sweat and feminine ardor overwhelming the atmosphere. White steamy cloud heads formed in the distance and rolled across the sky, testaments to the sensually marked perspiration that now dominated the planet.

Finally the entire horizon became filled with the twitching form of Hime's colossal pussy, it's dainty clitoris now resembling a planet of its own. Aoi couldn't believe his little sister was already so aware of her sexuality, much less willing to use it knowingly upon an entire inhabited world.

"I-It must be that Nina girl, I knew she was a bad influence on Hime- b-but-" He stammered, unable to even vocalize the thought.

To his own shame he realized that the combined sight and smell that filled all his senses had proven irresistible to his base instincts and he felt a growing tightness in his jeans.

Before he could even admonish himself or look away he fell to the ground as it heaved and shook beneath him. After several moments a great boom echoed across the city and he glanced up to witness the immense form of Hime's clit grinding forward across the planet, crushing everything beneath it.

Aoi could just make out the tiny bursts of aircraft popping against its surface as it slowly edged forward, and beneath it he could see the occasional massive spire in the distance collapse in an instant before it's unstoppable advance.

He had just enough time to look up and gasp as the miles-tall clitoris swept up and brushed his entire city asunder and lifted off the surface.

Hime shivered pleasurably as her clitoris lifted up from the planet, a small clear string of nectar draping across another thousand kilometers of the continent beneath it. Nina leaned in and smiled mischievously at the sight of a fine paste of gray cityscape adhered to the underside of her perky clit and caked inside the small wrinkles at its base.

"A-ah~ I can feel it stuck on there- It's so tingly." Hime said breathily.

Nina grinned. "Yeah, I made this one nice and special. Do it for me, huh Hime?"

Nina leaned onto her back and lifted her legs up to rest on Hime's shoulders, scooting her butt forward onto her lap.

Hime rubbed Nina's thigh  gently with her free hand and brought the planet towards her crotch gently. She pushed the sphere against her slick lower lips, using it to push the pink labia aside to reveal the lily of her womanhood within.

Each pass of the tiny world left another continent scraped bare and another stain of sparkling ruined cityscape coated onto her spread pussy.

Nina giggled, bringing her pinky to her lips and sticking out her tongue slightly. "Haah- that's good. Tell me how many of them do you think are in me now?" She asked, stilled smirking.

"I dunno- at least a few billion?" Hime replied, her thoughts drifting to the question of just how many microscopic people might still survive stuck to her clitoris or buried in the wrinkles beneath it.

Nina responded with a satisfied drawn out moan. "I love thinkin' about it-  Put more in me, come on~" She implored childishly, staring lovingly into Hime's eyes.

Hime blushed and turned the planet over in her hands, pressing the last intact continents into the Nina's waiting folds.

When the entire world had been scraped down to a lifeless marble Hime idly tossed it aside and reached for one of the others beside her.

"So- what should we do with this one, huh?" She asked plainly.