A mouse girl who is eight years young and going to school, when her Hyper genes activate and put her into heat. She is increasingly horny in the morning and doesn't understand the heat and growing need to breed, and her classmates can smell her increasing musk and scent. She doesn't know it yet but the longer she goes without breeding, the more aggressively her body pumps through puberty, beginning to make her chest grow breasts, her hips and butt grow fat, and her pussy and womb more fertile and ready. By the time her first class is over, her big plump butt fills the seat, and everyone is squirming and horny, infected by her scent. She sees the boys in her class are all sporting bulges in their laps, bulges she likes on a primal level, the sight of them and their own growing scents making her thrust/buck her hips almost subconsciously. Her butt visibly growing as she does.
She doesn't know that her scent is spreading out of her classroom and filling the whole school, and even out the front doors and into the city, and she certainly doesn't know that it is a powerful, hyper sex attractant. She doesn't know what's happening or why when she's called to the Principal's office and she's standing up, her skirt barely covers the bottom of her now plush ass, or why all the teachers and staff are looking at her with glazed eyes. When she gets to the office and is told to close the door, she does, not seeing the crowd of teachers, students and janitors gathering outside the door, breathing in the air, or how their bodies are responding to her musk. When the Principal tells her that she's in trouble, she doesn't know why he's unzipping his pants, or why his cock is so big. All she knows is that when he orders her to get under his desk and suck, her body is already obeying. Her mouth opens wide to take his cock in, her lips stretching, her tongue rubbing and licking as her head bobs up and down his shaft. All she can think about is the taste, the feel of his cock, and the musk he gives off. Her scent is transforming him as she sucks him off, making his body more feminine, even changing his gender identity. When he cums, she swallows, then sucks him dry, and she keeps sucking and sucking until her breasts begin to leak, then her nipples. It's not enough.
She has been in the Principal's office for almost half an hour, and the whole school is reeling. Boys and men alike are cumming, flooding their clothes, and then fucking and being fucked, and not just them. The women are cumming and cumming, flooding their panties and then dropping their pants, mounting anything they can find, be it another woman or a man. Even the mice girls and boys, too young to be sexual, are feeling the effects of the scent, and they're not just having sex. They're fucking, breeding, and the changes in the women and men are spurring the change in the children. The girls are getting breasts, the boys cocks. The children are breeding each other, and they don't stop. The effect has spread beyond the school, the whole city is going crazy.
She's lost track of how many times the Principal has cum down her throat, but her breasts are heavy, filled with milk, and her pussy is drooling. The Principal is moaning like a girl, begging for more, and when he pulls her head off his cock, her scent has made him a full, 100% woman. She's still got a cock though, and it's still hard, and when the new woman-Principal begs her to fuck her, she doesn't need to be told twice. She climbs up on the desk, pushes the Principal onto her back and spreads her legs. She pushes in, and both scream with joy, the Principal cumming, and then cumming again, and her little mouse girl is cumming too. It feels so good, she keeps thrusting and thrusting, not stopping, her cock never going soft, and her womb is so hot and so wet and ready. It's not long before the Principal has her legs wrapped around the mouse girl, her hands on her butt, and the two of them are kissing and cumming and crying and begging for more.
It's hours before anyone else gets to her. Hours of fucking and cumming and breeding and more, and by the time a janitor manages to open the office door, the smell is too much and he's forced to join them, taking the Principal's newly grown pussy, and then the mouse girl's tight asshole. It takes a few days, but the two manage to escape, the mouse girl and her new, pregnant lover, and they find a place to hide, to breed and be bred, and they aren't the only ones.
It will take months before the effects of the scent subside, and by the time it does, the world has changed. Men have been turned into women, and women have become more masculine. Mice and women and men are intermingled, and the children are growing, the women are growing bigger breasts, hips and butts, their pussies are growing more fertile, the men are losing their testicles, and the boys are growing cocks.
The mouse girl, however, she grows differently.