While you are looking over the class for your first test subject, your eyes land on Emily, the class nerd, and your best friend. You two have known each other since forever, being closer to brother and sister than friends. And, as siblings, you two have a right to know each other's deepest secrets- you were the first person she came out to as a Lesbian years ago. And, you also know her perfect OC.
You examine her current body. Messy brown hair, pale skin, acne riddled face, brown eyes, and a pudgy body. Also, completely human. She'd got her nose deep in her notebook.
You write her name down in the notebook, and below it write:
Emily will feel a sudden and intense need to use the bathroom and will ask the teacher if she can go. Once she enters the bathroom- which will be completely empty- she will start transforming. First, her hair will straighten, and grow to reach the middle of her calves. It will turn bright cobalt blue, and also transform into 20 large prehensile tentacles, which will start at 4 inches and taper consistently and smoothly. The surface of these tentacles will glow a radiant blue in the dark, giving her an alien air. Her ears will become three-inch-long elven ears which will move in response to her emotions. They will also be very sensitive- the slightest touch will be enough to send a burst of pleasure up her spine, and a dedicated massage will turn her into a metaphorical puddle of bliss. Only another person's touch will work, though, she won't be able to massage herself.
Then, her face will change, becoming a smoother, more elegant version of herself. Her eyes will become blue as well and gain an airy quality to them. Her lips will become plump, soft, smooth, and kissable. Her voice will change to be more melodic, and she will have perfect pitch, and be able to perfectly memorize and repeat any sound she hears once. She will have cute freckles on her cheeks, which glow with the same glow as her hair. She will shrink down to 4-feet-tall and will weight around 30 pounds whenever someone carries her.
Her hips and ass will expand dramatically, giving her a pear-shaped body. Her breasts will be small and tender, barely able to really be called breasts. More swollen nipples than anything else. Her arms will transform into bird wings, like those of a harpy. Her cobalt blue feathers will always be soft, clean, dry, and warm. Her legs will transform into an anaconda's tail below her hips, scaled up to be flush with the rest of her body. Instead of being green, her scales will be blue, like the rest of her body. This bulk will not affect her flying in any way- in fact, she is strong enough to lift big rigs with little issue and is capable of carrying them for days at a time. Despite this, she prefers to coil herself around her friend's midsections, making them carry her. She will become exothermic, relying on her environment for warmth. If she can't find sufficient warmth, she will either seek it out, or fall into a state of hibernation until she is warm enough. Excessive warmth will only make her more active.
Right where her two bodies meet, she has a small slit that is impossible to see unless you know what to look for- and even then, it is difficult. When she is aroused, or needs to lay eggs, this slit bulges up, forming a very puffy vagina. This will act exactly like a regular vagina, except for a few things: one, she won't experience periods- instead, once a month, she will lay an egg. If it is unfertilized, it will not be very big- in fact, it will be almost indistinguishable from a chicken's egg. If it is fertilized, the egg will be a sphere with a diameter of 1/2 a meter. Upon laying a fertilized egg, her entire demeanor will shift. She will become extremely protective of it, only allowing her mate to come near and touch it. She won't move from the spot she laid in, unless the mate moves the egg. She will also become indothermic, heat radiating off of her coils to incubate the egg. She will still keep her clingy ways, however.
Her mind will be mostly unchanged. The only thing that will change will be that she will start referring to herself in the third person, calling herself Vi-vi, whenever she experiences strong emotions. Her typical wear will be an oversized T-shirt with some sort of nerdy graphic, and a tight tube-skirt underneath it.
Emily, or Vi-Vi, will be completely aware of these changes, but her reaction to them won't attract any attention. She will be as aware of the changes made by this book as if she was using it herself at all times. She will also always be able to access it, unless someone else is currently using it.
"Um, Mr. Davenport?" Emily asks, looking up from her notebook, "May I go to the restroom?"
"Of course Emily," the teacher says, "Go ahead."
You hide the book inside of your jacket, as you ask for permission to go yourself. After getting in the hall, you realize something:
Emily's going into the female restrooms. You're a guy. With the power of the notebook in your hands, however, that fact is something that can be easily changed. You write:
(Your Name) will transform into a cute, sexy, and athletic female version of himself. It is remarkably easy to tell that it is (your name), despite the change in gender. She will be called Arizona.
Your change wasn't the deep, slow, orgasmic experience you were expecting- there weren't any waves of pleasure riding up and down his back, or a sucking feeling on your crotch. No, instead, one moment you were (Your Name), and the next you were Arizona. You only noticed the change by the fact your shorts were suddenly much shorter, and that your walking pace had sped up significantly. You reach the female restroom and knock on the obviously locked door. "Emily?" You ask. "Vi-Vi?" You try, just in case. Your voice is still recognizably yours, just with an added female tone to it. "It's me- are you okay?"