"I-I got this myself!" Natsuki tugged the sphere away in a fist - and pulled her eyes away, too. She twisted the little ball of purple around between two warm fingertips. "It's wet enough! Next!"

"Aaah... uhhmm..." Yuri took a moment to regain her bearings, looking lost. "I'd... I'd usually, slowly... Uhm, tease my..." She murmured under her breath. "...I can't say it..."

The petite student tapped her shoe on the ground. "Then... show me, idiot."

With all the bravery of a sheep walking into a pack of wolves, the tall schoolgirl removed her grey blazer, and timidly pulled the uniform's vest and undershirt up to her narrow collarbone. Undoing her lacy bra, both of her breasts sagged out: milky-white masses with plump, bulging areola. Not only did they bring the planets to shame; they surface area on each was a longer distance than any micro inhabitant could hope to traverse in three lifetimes. With her bangs fluttering over her shut eyes, she timidly pressed her own world upon the left nipple, stroking the bulging hill slightly.

Natsuki's mouth held open for a moment, gaping in fascination. "Woah... they're real? They're like dinner plates."

"Please..." Yuri balanced the shirt's waist with her delicate chin, bowing as if she were going to curl up into a ball and roll away. "Don't stare..."

"I'm - I'm not gonna learn unless I watch!"

"Natsuki... At least take yours off, too..." She shyly stole a peek. "...to follow along..."

With a defeated grumble, the twintailed young woman practically ripped her top off, layer by layer. They landed at her shoes in a crumpled pile - from her short blazer to her frilly undergarments - and she covered her chest with body hands for a moment. It didn't occur to her that she was flashing billions of microscopic people in the process; hiding them from Yuri was more important. Her frame was slight, narrow, and fluttery, like an agitated pixie. Finally, though, she lowered both arms to her sides, revealing a pair of perky pink nipples atop modest cups. Still, for anyone living on that planet, they outsized moons. "Yeah, I know. Go ahead and laugh at the flatty."

Now, it was the long-haired maiden's turn to gaze - as awestruck as the minuscule inhabitants, looking at the distant, fleshy wall. "...Adorable... I'm jealous."

"You're doing it again! You're making fun of me, jerk!" She squeaked, holding her hands up to her tits again.

"N-no! I would never! E-especially when my friend's revealing her vulnerable places..." Yuri fidgeted with her hair. "...your posture is healthier. And once... I read that... smaller ones... are more sensitive!..." She appeared lost in the clouds for a second, driving her own planet deep into her nipple. She spun it in small orbits, pressing deep against the massive dimple; before coming to her senses and blushing. "...Ah! I w-wasn't -- F-forget what I said!"

For the first time in a while, a wide grin illuminated Natsuki's face. "Ahaha, it's already out of the bag! Of... of course my boobs are great!" Her chest puffed out proudly, and imitated Yuri's rubbing motions by slamming the entire world into her right nipple's round tip. She laughed at the tingling sensation of ancient cities' rooftops and mountains - feeling them past the force field, burying them into her milky pores. "Tiny! Fierce! And y-you're getting a rare chance to see 'em in action!"

Watching her snappy, ecstatic motions, the taller woman moved her teensy planet away from her melons... and pushed it in the orbit of Natsuki's boobs. "Huhu. Is that so? Then I shan't waste it~" She experimentally brushed her companion's left breast with the cotton-candy-coloured ball, tracing delicate outlines around the edges before spiraling into the center. Every twist made the girl pant a little quicker, as the ball started to gather up her growing perspiration.

"Eeeeyah! No fair! That was a sneak attack!" Struggling to hold herself in the seat under the mounting tension, Natsuki suddenly struck back - nimbly pushing her own amethyst toy on the heaving bosom before her. She squeezed it in deeper, distorting the bulging mountains with quick, intense rubbing. Again and again, the minuscule populace - from the upper classes to the homeless - fell off their feet from the shaking impacts against the spongy, receding tissue of the titan's towering tit. Even if it was soft and malleable, its sheer scale rendered it impossibly dangerous. Without the force field's protection, their vast plains and endless oceans would instantly be a smudge on a young woman's chest.

In the meantime, Natsuki's twitching and fidgeting slammed her nipple against the coral-coloured continents' sky again and again. The thin disturbances and cracks only grew more vast - letting in salty sweat drops off her petite form, crashing into their minuscule oceans.

Yuri shuddered and mewed under the continual squeezing and toying with her bosom. Insane pressure and heat built up from within her - translating to scorching heat waves across the purple planet. "Ahhn... N-Natsuki..." Her eyes were pleading and small, quaking in ecstasy and hesitation. "...I...I want to feel them against... both at o-once..."

The sudden outburst took her companion off-guard; her pressing and teasing grew harder as her cheeks flushed up brighter, pupils locked on her. "...Yuri, you greedy... hah... You're supposed to be teaching me! A-as if you can hog all the fun yourself--!"

In a single breath, both club members stood from their seats; held the marble-sized worlds close to their chests; and wrapped their arms around each other. The worlds were now both hanging in a warm balance between their embrace. The purple realm of ancient legends was pinned between the mighty mountain of Natsuki's flat left tit, and the cascading flesh of Yuri's right. Meanwhile, the rolling pink fields of the other orb had its east hemisphere engulfed in the smooth mounds of Yuri's left breast, and its west assaulted by the twisting, twitching mass of Natsuki's right. The shorter of the two stood on her tiptoes, while the taller one leaned down, keeping their hearts close.

They both brushed their breasts together while hugging. Long, heaving breaths from Yuri's mouth entered Natsuki's upturned nose, as the latter's fingers clutched the former's shoulders with an unspoken desperation and hunger. The two brushed together, causing the breasts to jiggle, and shock waves to traverse the oceans of the twin worlds. Natsuki's tender teats grew erect and stiff, pinning either of the populations with greater and greater pressure. Meanwhile, Yuri's mammaries began leaking from the stimulation, thin traces of feminine juice washing into the creaking protective fields. If the balance shifted too far to one direction, the energy barrier might be pierced. They could be flattened briskly by a small bust; or drown in a vast, salty sea of love juices.