Four friends stood in front of the their fifth friend's house... except that calling it a house didn't do it much justice. It was more of a mansion. Alyssa, the resident of the house, was a famous inventor at the age of 15. She found inventing a fun past time while her parents helped her get patents for the more helpful ones. Despite her intelligence, Alyssa's parents wanted her to go to high school so she didn't fall behind socially. Alyssa ended up attending at East Ruby high school. She excelled at classes and was nice to her fellow classmates but didn't seem to get along with them in a friend sort of way. That is until she joined her school's anime and video game club. The small fact that Alyssa liked anime and video games surprised most people, they figured a super genius like her wouldn't find that appealing. She quickly made friends with four other girls in the club. Lisa the freshman, Sally and Jenny the sophomores, and Sophia the senior. The girls started hanging out in and outside of the club which lead to the discovery of Alyssa's lack of a sleepover.

"You've never had a sleepover?" Lisa asked.

"Yeah, this is my first time having friends." Alyssa said meekly.

"Well, that's unacceptable!" Sophia exclaimed. Sophia was always the most excitable of the group. "We have to get your first sleep over going! Who's with me?" She asked. All the girls raised their hands. "Alright, where should we have it?"

"My house is pretty big, I have the basement to myself since it's also my lab/workshop." Alyssa said texting her parents for permission. They sent back a quick thumbs up emoji. "It's cool with them and I'm working on something that should be done by next weekend, let's do it then." Alyssa informed everyone. They all gave a nod and they went their separate directions.

A week passed and everyone met at the address Alyssa gave them to find a mansion. "W-well, who's gonna ring the door bell?" Lisa asked.

"I-I'll do it." Sophia said. She pushed the button and a normal sounding chime went out.

Alyssa met them at the door soon after. "Hey guys! Welcome to my house!" She said welcoming them in.

"You call this a house? This a mansion!" Sally exclaimed. "I'm so excited to have this sleepover!"

"I am too!" Alyssa said, "In fact, that invention that I've been making was for this. Follow me." She lead them down into her lab, past numerous unfinished contraptions until they came to what looked like a computer with a spout hanging over little bottles. Next to it was what looked like a metallic changing booth. "I call it the Morph-O-Matic! All of your anime dreams can come true by transforming into the characters!" She said waving towards the machine. "I've tested it on myself but the question is, would you guys like to try it?"

A stunned silence rang through the room. "Really, anyone?" Sophia asked.

"Yep, most of the time was spent on add characters, mainly ones from games and shows we know." She explained.

"How does it work?" Jenny asked.

"I'm glad you asked. How it works is, you select a character and then the system makes a serum to change your DNA into that character for a limited time and then it'll return you to normal. You can set how long it lasts as well." She explained.

Lisa meekly raised her hand which Alyssa pointed at, "What's the machine next to it?" She asked.

"That's a good question. That's just a scanner to record your info so just in case something isn't the same when the transformation is over, we can fix it." Alyssa said. All the girls crowded around the machine to try something out before an error blocked them. "Right, you have to get scanned before it'll let you make a serum. Besides, I have a little game that I'd like us to play." She told them. One by one the girls entered and got scanned. When they exited, they saw a read out on themselves.

Name: Lisa
Age: 14
Height: 5'1"
Weight: 90lbs
Cup Size: Flat

Name: Sally
Age: 15
Height: 5'5"
Weight: 120lbs
Cup Size: A cup

Name: Jenny
Age: 15
Height: 5'6"
Weight: 110lbs
Cup Size: B cup

Name: Alyssa
Age: 16
Height: 5'7"
Weight: 135lbs
Cup Size: BB cup

Name: Sophia
Age: 17
Height: 5'10"
Weight: 125lbs
Cup Size: DD cup

With all the girls recorded, Alyssa gathered them at a table. "So this is the game I want to suggest," She said sitting down with them. She put a lazy susan on the table, A small robot set out five cups on it. "We have all watched Monster Musume, so I've thought of a game. In these cups are serums to change us into Miia, Papi, Centorea, and Rachnera but the fifth cup transforms someone into Kimihito. This will basically be a game of tag with a time limit. Whoever turns into Kimihito must run away from the girls for thirty minutes. The girls must plant a kiss on Kimihito lips to win. The first one to get this kiss or survive can choose the first video game we play tonight." The girls lit up with excitement. "So, the rules for the transformation round are simple. Spin the lazy susan and pick a cup. I suggest getting away from the table just in case you pick one of the girls." Alyssa said.

Everyone looked around at each other, daring each other to drink when Sophia spun the lazy susan. "I'll bite the bullet. I trust you Alyssa." she said. The lazy susan stopped and she opened the small cup and chugged it straight down. She stepped back in anticipation when she suddenly said "I feel all tingly!"
Everyone looked at Sophia's blonde hair as it turned light blue. It retraced  into her skull from her hips until it was almost shoulder length except it was  more spiky in the back. One long strand lifted itself up into a cowlick. Her facial features softened up as her face went from an adult to a ten year old child.  Her green eyes changed to an orangish-gold.
"I'm gonna be Papi! I can't  wait to fly around!" She said with excitement.  She looked at her hands and arms to see them shrinking. She turned to face the mirror Alyssa had put up to see that her whole body was shrinking as well. "Lisa, come stand next to me!" She said to the young freshmen.  Lisa stood next to her as Sophia grew shorter and shorter until she was 5'2".

"You're still taller than me!" Lisa pouted, tired of being the smallest of the group.

"Well, think of it this way.  When you take you drink, you'll be taller than you are now!"  Sophia said with the same enthusiasm as Papi. As she talked to Lisa, her voice started changing to match that of Papi's voice actress.  Sophia felt another tingle as she put her hands on her breasts which began shrinking. Her hands got closer to her body as she shrank from a double D to an A cup. Her body and appearance matched that of Papi almost to a point except two thing.

"You should be growing wings in 3... 2... 1..." Alyssa started counting down. As soon as her countdown stopped, Sophia felt the same tingling in her arms. She looked to see her new skinny arms growing longer from her elbows. and they kept growing until they reached the same wingspan as Papi. Everyone ran over to feel the new arms, touching them. Lisa poked one spot that suddenly erupted in blue tuffs. These blue tuffs starting growing all over her arms, soon they grew down into actual feathers. For the final touch her fingers merged together into her new arm, revoking her of using anything that needed thumbs. She then felt a tingle in her legs and feet. "If one of you could help me with my pants, we can watch my legs." She said to everyone. Jenny rushed over, unbuttoned her pants and slid them down.  At the middle of her thighs, her legs started to turn yellow and harden. It continued down her legs when her feet started to change as well. Her toes stared to grow in size and merged until they were just three digits instead of five. Her toenails turned black as night, they turned sharp and turned into talons. Sophia stood there, a perfect replica of Papi. "This is so cool! Sophia/ Papi said. She started flapping her wings and took off.

She flew around the lab to the excitement of everyone, While distracted, Sally spun the lazy susan and drank. Sophia landed as Sally slammed her drink down on the table. "Let's do this!" She said flashing a smile. The smile showed off her changing teeth which were growing sharper and sharper and her tongue got longer and longer. Her black pixie cut hair turned red as it started growing longer and longer until it reached her hips.  Her brown eyes shifted to a amber color as they grew slightly larger. Her facial features softened as her face changed to fit the character. Her ears grew out to a point and turned red. Sally noticed that the world was slightly lowering until she realized she was getting slightly taller. When she stopped she was only three inches taller.  Her arms and body made subtly changes until her hips expanded out quite a fair bit.  

"My mom would say these are nice birthing hips." Sally said out loud. Everyone gave her a weird look. "My older sister is keeping my mom from being a grandma. She's not happy about it." She gave as an explanation. Sally looked at her new features until she felt a small tingle in her chest. She unbuttoned her shirt as her small breasts started swelling. Sally bit her lips as her chest swelled and swelled. She let out a moan as they reached F cup. "That was amazing." She said in a voice that wasn't her own.

"Sally, if you could do me a favor, please lie down over here." Alyssa said pointing to an area. She walked over, took off her pants and panties, anticipating what was next. She laid on her back as her legs came closer together. Her toes started to merge together as she felt her spine become stronger to support her tail.  Soon, any trace of legs were gone as scales covered up her new mass. Sally quickly check to see if one of her most important parts made the journey. A small surge of pleasure told her it was still there. Her tail started growing longer and longer. Alyssa got out a tape measure and started following it. When it finally stopped, Sally's new tail was 22 feet long. "Impressive, let's get you back up to slithering so we all have equal ground." Alyssa said.
After a bit of training, Sally was moving like a pro.

"So who's next?" Alyssa asked.

Everyone stared at the three cups remaining when Jenny spun the lazy susan.  "I guess there's nothing to lose" She said as it stopped. She drank from the cup and waited. She looked into the mirror to see... nothing.

"Alyssa, I think is one was a bad..." She started to say when she noticed her brown hair turning black. "Oh no." She thought to herself. She grew from her normal height to only an inch taller. Her green eyes shifted to brown as her face reshaped itself. She felt her throat tighten as an Adam's apple grew in, changing her voice. "This is super weird!" She said in Kimihito voice. Her body started bulking up and hairs appeared on her body. Her breasts started shrinking back into her body.  Her change was almost complete except for one thing. "I-I don't feel comfortable showing the last change in front of everyone." She explained to everyone. They all understood and watched as she entered the restroom. Jenny pulled down her pajama pants and panties, which she took off for good measure. She felt a tingle in her loins. A heat washed over as her genitals started changing. Her clitoris started shaking as it grew out and thickened. Her ovaries pushed their way out turning into  her ballsack. Her eggs became semen filling her nuts. Her vagina sealed up as the tip of her new cock opened up. A rush of pleasure rippled through her body as he came. His breath was hitched from the excitement. After he caught his breath, he cleaned up the mess he made and exited the bathroom, fully male.

"If it isn't the man himself." Alyssa said looking over to him. "How does it feel?" She asked.

"It was an experience to say the least." He explained. Jenny sat down at the table at the table and asked, "So, whose next?"

The transformed group looked at the two untransformed members.  Lily had a frown on her face unlike any they had seen before. "I-I might not do it." She said in a weak voice. "It just scares me a bit. You're all completely different now and what if we never change back?"

"Lily, I'd never let us do this if there was no way to change back. Also, these serums only change appearances, not who we are. I'm not going to force you to do this." Alyssa said hugging the young freshman. The rest of the company joined in.

A couple seconds passed before Lily said, "Thanks, My anxiety was getting to me. Now let's do this!" She said spinning the lazy susan. She opened the cup and chugged it before fear could stop her. Her short ginger hair exploded out turning golden blonde. Her ears stretched out and became just a little bit longer than Sally's ears and brown instead of red. Her lightly tanned skin started turning pale. Her amber eyes turned blue and grew larger as her face reformed. "I must fight for my master!" Lily said as her voice matured into a fitting match.  Lily started to strip down knowing who she was changing into. Her arms started to change, bulking up a little when she noticed everything was lowering itself. Alyssa started growing taller. She stood next to everybody as she grew taller and taller. She stopped stretching at 6' 7" and lorded over all the girls and the one guy. "Wow! I'm so tall!" Lily said looking around.

Alyssa leaned over to Sophia and said "It's hard to imagine that you're a senior and she's a fresh man."

Lily began feeling her legs as little brown hairs grew on them. They quickly covered her legs all the way up to her midriff. Her toenails turned black and started covering her feet. Soon, they wrapped around and became hooves. Lily's legs started getting bigger to accommodate what was coming next. A tingle on her butt informed her of what was coming next. Her hips and ass expanded out past the point the point of being sexy. It grew bigger and heavier, almost making Lily  fall over until a second pair of legs grew from the mass. The new legs touched the ground and Lily stabilized herself, on her behind sprouted a tail the same color of her hair.
A warmth grew over Lily as her vagina twitched. Everybody turned to look, except jenny who turned away to be nice, as it moved down her body to her rear legs. As it got closer, it became harder and harder for Lily to keep quite. She let out a long moan when it finally stopped and change to match that of a horse. "And now, for the main event!" Lily said excitedly. She put her hands over her nipples as her breasts expanded. This time she didn't stay quite as her flat chest became bigger than she could ever imagine. She quickly returned back to her normal attitude and found some clothes to cover her new I cups.

"That leaves one girl and one drink for me" Alyssa said, not having to spin the lazy susan. She chugged the drink and set the cups next to the four others from her friends and went in front of the mirror. Her brunette hair turned lavender and her eyes turned red as blood and her pupils disappeared. She turned around to the others as four more eyes opened up. She smiled and showed her teeth sharpening and  turning into fangs. Needless to say, everyone quickly cowered. She started to walk towards them as her body stretched, making her taller. She reached a height of 6'6" as her hands turned black as night. Her fingers sharpened into claws. A tingle in her back and midriff told her that her first thorax and abdomen grew in.  Her arms hardened as her exoskeleton began to grow. The exoskeleton grew around her butt and expanded into her second thorax. Eight new legs sprouted from them and lifter her up as another segment of her exoskeleton grew in. This time it was her second abdomen with Rachnera's pattern on it. A strange feeling on her abdomen told her that her spinneret grew in.

To test this, she quickly shout out some webbing, trapping Jenny in the seat he sat in. Alyssa cut the strong silk and said in Rachnera's voice "Better make sure that this doesn't happen in the race. The exoskeleton crawled down her human legs slowly changing them into her pedipalps. Her feet curved and her toes merged into hooks completing her lower body changes. "One last thing." Alyssa said taking off her shirt. She had guess correctly as her medium size chest grew to an H cup, marking the changes as complete. Alyssa quickly began making clothes to fit their new bodies.
"How do you know how to do this?" Jenny asked looking at the new clothes.

"An arachne was my first test form so I learned how to make clothes." She explained, putting on a tank top. "And now, let's begin.  Jenny, you have five minutes to hide." Alyssa said starting a timer.  
Jenny ran off to hide in the lab as the girls stretched out.

"There's gonna be no hard feelings about what happens right?" Lily asked, galloping in place.

"Nope, we're super durable in these forms so we can go all out. No need to worry about the lab either." Alyssa explained looking at her claws.

"Good! I'm gonna leave you all in my dust!" Sophia said taking off.

"May the best girl win!" Sally exclaimed as the counter reached zero. The girls tried to take off but quickly found that they were ensnared in webbing. Alyssa took off as the  girls tried to cut themselves free. Sally was the first free herself and take off in another direction. Sophia cut herself free with her talons.  Lily got free eventually and took off.

The race kept going as the timer counted down. Sophia dive bombed people and  Sally tripped people with her tail but none of them seemed to find Jenny.  Sally reached the bathroom and said "I just can't find her and I can't hold it anymore!" She opened the door to find Jenny sitting there, looking at his watch. Their eyes met for a moment before Sally seized her chance. She quickly embraced his lips with her own. "I win, and no one else kissed my girlfriend. By the way, we should tell them today." Sally said.

"I agree, now hopefully this wears off soon." Jenny said.

"Why?" She asked.

"Seeing hot girls run around nearly naked is one thing but when you have an indicator is worse." She said looking at the bulge in her pants. Everyone quickly reassembled in the main area next to the machine, already showing signs of detransforming. "We have something to tell you," Jenny said holding Sally's hand.

"We're dating." Sally finished for her. Congrats were heard all about as they returned to normal.

"So Sally, you win! You can pick our first game for the night or transform one of us." Alyssa said waving to the machine.

Sally thought for a bit and finally said "Transforming someone is too much power for me to hold so I say we play smash bros first!"

The girls agreed to the game, as it loaded up Alyssa said "Do you guys wanna make things interesting?"