Emy was a normal girl, a bit lean and wasn't very social, she was walking to home, feeling her arm painful, a spider has bite her while she was in a school trip to a genetic lab, she don't talk to nobody, she thought it was nothing, when she goes eat her dinner her mother ask about her injury, she said that's nothing and go sleep, during the night she didn't awake, the spider bite made her body change.
Her was sleeping while changing, body take a more feminine hourglass shape, her chest, butt and hips grows, her groin tingling and her grew new organs during the night.
When Emy awake she feels strange, her head hurts and she butt is strange and... full? She get out of her bed, her Room was a mess, like aways, then she look in the mirror, and realize her changes. Surprised by her own image, she analyze her new body, long black silky hair, C breasts, a big and round butt and big hips, when she feels something wrong, Emy feel something sticky dripping from her butt, coming from inside her... and more is ready, she pulled down her pants and looked at her butt in the mirror, she felt something trying to get out and put force into it and her butt start shooting a thick and sticky rope of white silk, while it shoot, Emy cum by the pleasure, she continues shooting until her butt stops by itself, feeling her new muscles closing her web butt.
Now she is standing, totally confused and scared, but at the same time curious by her new body ,with a thick rope made of webbing coming from her ass stuck on the wall. When she tries to hold it with her hands she find that the web that came out of her butt Don't glue in her hands, when she pulls, more web comes, she keeps pulling her webbing, it seems almost infinite, she focus on her new hole and the web there just stops.
Emy turns back to the mirror again and look at the big opening in her butt right below her anus, she tries using her unusual hole again and try shoot more silk, with a thought a rope of silk hit the wall and covering it with white silk in the process, she tries and learns new ways to shoot web, then she feel her ass empty, meaning that she don't have much silk left.
"Wow!"Emy thought, she can shoot silk from her back side like a spider girl, a horny one.
Feeling herself very horny Emy fingered her muf, she feel her web butt filled itself with silk again, she turn herself and start spraying a thin sheet of silk from her butt over her room making everything white.
hen she heard someone, quickly, she spray webbing over the door to seal it, and someone knock the door "Emy, honey, are you okay?" was her mom probably worried about her,"no, mom,i don't feel well, I'm not going to school today" "ok, i need go to work, honey, you will be fine?" "yes mom i wll" hearing her mom goes she and go back masturbate herself, minutes later she came, squirting girl cum and spraying webs, making her room white, her "Nest", she was acting like a spider, but she liked it.
After cleaning her room from her webs and cum, she search for other powers, no super strength, no super reflexes, no spider sense, no wall-waking, she only have her butt silk.
"This isn't fun at all"
Now whar happens next...