"1, 2, 3, 4, 5, 6, 7! 1, 2, 3, 4, 5, 6, 7!"

"Okay! Good work everyone! I think that's enough for today, girls..." Chika Takami let out a heavy sigh as she stretched her body a final time before falling to the floor. The other members let out similar sighs of relief as they sat on the school roof together.

The school idol group Aqours had just finished their daily dance routine. Each of the girls wore their usual workout attire, but today was a particularly scorching summer day, so their temperatures were running a little hotter than normal. Slumped in the corner, covered in sweat, was Ruby Kurosawa, seeming a little more exhausted than the others.

Being the smallest member of the group, doing a lot of the more physically straining activities of an idol was a little more difficult for her tiny frame. On the outside, Ruby looked to be a frail little girl, but she truly did have a pride and passion for idols that any proper school idol would. Ruby loved that even a timid girl like her could participate in something so much bigger than herself. And to be able to do that with her older sister Dia and all her friends was truly something she savored.

"Ruby, you did great today! I'm so proud of how far you've come. Same to the other first years!" said Chika with a proud smile. Ruby was happy she got her senpai's approval.

"Of course my precious little sister did well, she's a Kurosawa! My lovely little shining Ruby and I will be the brightest idols someday, desu-wa~" said Dia in a haughty voice.

Chika gave a lighthearted laugh in response, taking Dia's enthusiasm in stride.

"Ruby is truly like a little gemstone. The shining jewel of Aqours!" Chika said as she looked at Ruby, giving her a sweet smile. Ruby blushed in response, feeling a bit embarrassed at the sudden attention.

"Wow, that was pretty corny, Chika. But I do agree," said Kanan.

"Hmph, as do I. A little gem befitting a Little Demon such as herself~" said Yoshiko, striking a pose.

"Oh, what I'd do to have a cute little sister I could dress up and play with like you Ruby!" said Mari, ogling the redhead's petite body.

"Sorry Mari, she's all mine~ Ruby does make a precious little dollie though. I remember when we were little, Ruby would alllllllways let me pick out her clothes and do her hair. She couldn't even pick out her underwear until l--"

"O-okay, Onee-chan that's enough! You're embarrassing me..." Ruby's face turned a bright red as she curled up and hid behind her knees.

Dia felt remorse for a moment before a soft smile came over her face.

"I'm sorry. I know I get a little carried away sometimes, but you know I'll always be your Onee-chan, and you'll always be my precious wittle Wooby~" Dia cooed, giving Ruby headpats and squishing her cheeks like a child.

This didn't help Ruby's embarrassment. Her cheeks were red hot with shame, and it felt like steam was rising from her head. She didn't like being treated like a child, especially in front of all her friends.

--

Minutes later, the other girls were already discussing other topics as Ruby stayed huddled in the corner of the school roof, looking up at the bright blue summer sky. It was an intrusive thought, but sometimes Ruby felt like the others took her for granted. Like they only saw her as a pretty little doll to gush over. She shook her head, trying to keep her mind from going into a depressive spiral.


*cough, cough*

A few small, weak coughs escaped Ruby's lips. She wondered if maybe she was catching a summer cold but figured it might have just meant she was dehydrated.

"Want some water? You don't look too good..." Ruby turned to see Hanamaru handing her a half drunken bottle of water.

"Thanks, Hanamaru... I'm okay, just a bit more tired than usual. I think I pushed myself a little too far toda- cough" As Ruby put the bottle to her lips, an itch in her throat caused her to cough, interrupting herself.

"A-are you sure you're okay? You honestly look a bit red in the face... Maybe you should check to see if you have a fever. Let me call your sis--"

"No! It's okay. I'm fine. My sister would just get overly worried. I can take care of myself..." said Ruby.

Hanamaru was a bit stunned for a moment, she had never seen the little redhead be stubborn like this. Ruby stared up at Hanamaru, who had been bending down to look at her. Despite their same age and height, Hanamaru's chest was noticeably large for a first-year high school girl. She could have easily competed with the third years in that department. Not to mention her plump thighs and toned legs...

It was at that moment that Ruby realized she was giving her friend a pervy glance, but Hanamaru didn't seem to notice, only giving her friend a relaxed but worried smile.

"Still Ruby, we don't want that cough developing into a cold..." Hanamaru said quietly.

All the way on the opposite end of the roof, Dia's ears perked up at the mere mention of the word.

"Cold? Who has a cold!? Is it my Ruby?" Dia said as she began to walk over to the two first years.

"Ah, no Dia, it's umm..." Hanamaru whimpered.

"Onee-chan, I'm okay... it's not a big... big... achoo!" Ruby sneezed, once again unable to finish her sentence.

"Coughing and sneezing... and your face looks red... you're probably burning up as well. This summer heat wave can't be helping... We're going home, now!" proclaimed Dia, grabbing her little sister's arm forcefully.

"Wait, no! Onee-chan, stop!" cried Ruby, tears welling up in her eyes.

She felt the pitying stares of the other Aqours girls as she was dragged to the roof's staircase leading to the school. Despite the others just seeing an older sister acting out of concern for her younger sibling, Ruby felt a tinge of humiliation. Her brain was spinning things in a negative light. Were they all secretly laughing at her for being so weak? Fragile, like a doll. She made eye contact with Hanamaru, who gave her a soft smile and a wave goodbye before getting obscured by the staircase steps.

"I hope Ruby feels better soon..." said Chika in a concerned tone. The seven girls left on the roof said their goodbyes after that and went home for the evening.

Ruby felt a sense of powerlessness overcome her. By the time they left the school grounds she was holding onto her Onee-chan's hand like a child.

"I'll make you some supper and get you to bed. But first you'll need a bath. You're covered in sweat. Well, I am too I suppose. Do you want me to help wash you? I already have a cute set of pajamas in mind for you," Dia went on in a doting, motherly manner.

"*cough* I can do all those things by myself..." mumbled Ruby, but she wasn't feeling well enough to argue. Not that she'd ever talked back to her sister.

Dia was smart and beautiful. And a wonderful idol. Ruby looked up to her older sister, figuratively and literally. She had an amazing figure, and a style to go along with it. As they walked, Ruby couldn't help but notice the disparity in their bodies.

Despite only being two years older, Dia was voluptuous, having one of the womanliest figures of the group. And she had a delightful beauty mark placed perfectly on her cheek to add a cherry on top. Only Ruby knew however that her older sister had another secret beauty mark on her ass. She was the ideal School Idol from top to bottom. Ruby on the other hand could have easily passed for a scrawny middle school student if she wanted to.

As they walked, Ruby's stride began to noticeably grow shorter, causing Dia to take smaller steps as well. Looking behind her, Dia was shocked to find out what was happening under her nose.

Ruby had shrunk. A lot. She was already a small girl at 4'11 (152 cm), but now she couldn't have been more than 4'2 (127 cm)! How could this have happened without Dia noticing!? It must have been extremely gradual, because Ruby didn't seem to have notice yet either somehow.

"Ruby... are you feeling okay...?" Dia asked calmly.

"I'm-- *cough* okay Onee-chan, just feeling a little dizzy..." replied Ruby weakly. Her voice a slightly higher pitch than usual.

--

The sisters arrived at home and instead of drawing a bath, Dia changed her sister straight into her pink polka-dotted pajamas and sent her to bed early. It had been a while since Dia had changed her imouto's clothes. It made her a bit nostalgic. Seeing that Ruby still wore a very childish training bra and kiddie pink panties made Dia giggle.

This entire time Ruby hadn't questioned the large decrease in height. Only taking quick notice that her PJs were a little baggier than usual. Her cold had developed quickly, and she was too out of it to realize she had already become the size of a toddler.

Worried for Ruby's safety, Dia slept in the same room as her sister, in a futon next to her.

"Onee-chan... Onee-chan... mmgf..." Ruby muttered in her sleep before her eyes slowly opened.

It was the middle of the night, or at least she thought it was. Everything was dark, and the air was hot. Ruby thought it smelled like... her? She felt around, it was nothing but cloth everywhere.

"Are these my clothes? How did they get so big..." Ruby wondered to herself.

There seemed to be moist spots in the clothes, and Ruby feared she may have wet the bed again. But she soon realized that it was sweat, or at least she hoped so. Did her fever really make her perspire that much? It was then that Ruby realized she was stark naked, so these must have been her clothes after all. But that didn't explain their size...

"Onee-chan?" Ruby called out. She realized it wasn't just dark, but she truly couldn't see anything!

Ruby was at least relieved her fever seemed to have broken overnight. But she wondered where exactly she was. It was like a world of fabric surrounded her on all sides. There was a bit of trepidation, but Ruby began climbing the wall of fabric hoping to understand what was going on. Reaching the top, Ruby's eyes grew wide, she had no idea how to process what was she saw.

She was standing on a mountain of her own pajamas. She realized what she woke up in was her own pink training bra cup. Her futon stretched on forever in front of her like a bizarre cotton landscape. The walls of her room felt like miles away. The shortest school idol had somehow shrunk!

Ruby screamed, not knowing how to handle all this information. How did she shrink!? What was she going to do!? The red-haired girl tried to suppress it, but she couldn't help crying.

"W-what's going on!? Onee-channn! Anyone!" Ruby cried out to the darkened world of her own bedroom.

"Mmm... Ruby.... Here... you do it like thisszzz..." Ruby turned around to see the giant figure of her older sister sleeping in a futon next to her.

It both relieved and scared her to see her sister, now impossibly large. She was like a sleeping mountain. Dia was muttering in her sleep, it was a trait both sisters shared.

*snore* "Ruby... here... I'll keep you safe..." Ruby heard her sister whisper in her deep slumber.

Tears continued to fall down Ruby's cheeks. She wasn't sure what was going to happen, but knew she needed to get her sibling's attention. Surely Dia would help her. Ruby's thoughts went back to yesterday, at her snapping at her sister. She thought about how unfair this situation was. Why was this happening to her? Ruby wanted some independence, and now it seemed like she needed to get her sister's attention to save her life.

Ruby looked back up at her sister. A determined look appeared on her face. She wiped her tears and sniffed her running nose. This was no time to cry! Ruby knew she had to suck it up and go. She estimated herself to be roughly around 5cm. Looking at the downhill slope created by her pajamas, Ruby braced herself and jumped!

Sliding down her pile of clothes, Ruby couldn't help but find it slightly fun. Maybe being this small wasn't so bad. Her mind wandered to other things she could do at this size. Eating desserts the size of swimming pools, or playing inside her old dollhouses. She thought about licking a giant lollipop for an entire day and not even going through the whole thing!

Her tears had disappeared by now and Ruby was back to her usual self, a silly smile on her face. Perhaps she was just trying to avoid thinking about the obvious fears, but it was working.

Walking across the bumpy tatami mat, Ruby made it to the futon her sister was sleeping in. Dia was turned away from her, and Ruby was near the center of the futon, near her sister's waist. The outline of Dia's curvy body made for an impressive mountain range. Her sister's bare shoulders and feet were uncovered, which made Ruby wonder if her sister slept in the nude. She didn't remember her doing that when they slept together all the time as kids... A shy blush overcame her cute face, thinking about such topics. There was nothing to be embarrassed of since they were sisters, but they were past the age where seeing each other naked wasn't something to be conscious of.

Ruby thought about where exactly she should start climbing to get her sister's attention the easiest. No matter what, it would be tough, but Ruby was ready.

...Or so she thought. She soon realized right in front of her, underneath the layer of futon, was her older sister's large ass. It was the main culprit behind the curvaceous mountain range. It created quite the alluring curve, even Ruby had to admit. The large shadow it cast on her covered up the small amount of moonlight shining into the room, making it even more impressive looking.

The tiny redhead shook these thoughts out of her mind. It was time to act, she needed to get her sister's attention whether she liked it or not. Ruby crawled under the futon blanket, and entered a whole new territory...