Ty soon had a pretty obvious idea- as a rather shy boy, he'd hardly had any interactions with girls, so was pretty curious about them. It occurred to him, your sex is the result of an even chance and yet it makes your life so dramatically different. Why not wish it had gone the other way for him?
He undressed, eager to watch his body change as it happened, and wished to himself to turn into a female version of himself.
His heart started racing, his body soon feeling weird and tingly all over. It was like combining taking some weird drug with getting really horny, and it felt indescribable. As he looked over his naked form, which seemed to convulse with his heavy breathing, it seemed fuzzy, like it was his and not his at the same time.
A moment later it started to change. He would've thought his body transforming should hurt, but like puberty the changes felt imperceptible, though with how dramatic they were he could see these changes easily. His face shifted, the skin softening and the jawline smoothing, and hair extended down to his shoulders and back. At the same time, elsewhere on his body the little hair he had seemed to thin or outright vanish. His proportions then seemed to change, as he lost a few inches of height, his shoulders shifted inwards and his hips expanded outwards. The muscles in his arms and legs thinned slightly, too, and his hands and feet shrank a little.
He could tell his body looked far less masculine than it had, but even if he felt less like a boy, he didn't totally feel like a girl yet. And yet, he wanted to. Changing like this had felt so different, but he couldn't get enough of it. His wish had made feminine desires emerge inside him, and he wanted so bad to satisfy them.
The changes caught up with this just as soon as he thought it, and a little, high-pitched gasp of pleasure escaped his puffier lips as his hard cock twitched and he felt a warmth in his chest. He watched as his nipples grew wider and perkier, and then felt an odd sucking inside him as his balls moved up inside him, readjusting more and more as they went.
Instinctively, his hands went to his chest, and as he rubbed and pinched at his nipples he moaned eagerly. Under the touch, she felt her breasts start to form. She- it felt right to use that term now. She had emasculated herself, sacrificing masculine power for feminine pleasure. She watched eagerly as her chest grew, and his penis shrank, what remained of it feeling more and more sensitive as it went.
She was becoming the second sex. Ty had heard some book called womanhood that, and he had kinda gotten why, but she realized it felt right in a totally different way now- it felt like an advancement. As a boy, the first sex, he had been able to feel quite a bit of pleasure and arousal. But as a girl, the second sex, she felt far, far more, and it felt so natural to her.
As Ty's penis finished receding into her and formed her clitoris and her scrotum opened into a vaginal slit, she realized another way it felt right to think of this as an advancement- she could bear life. As a boy, he could cum in others and fertilize them, but as a girl, others could fill her up and pleasure her, and her body would carry their seed. Others would desire to fuck her, to mate with her, and the thought of their desperate horniness and their big thick cocks was empowering, it turned her on, it made her teasing of her new parts feel all the sweeter...
Suddenly everything seemed to go white, and she heard herself moan and then pant heavily. When her eyes focused again, she saw a sweaty girl in the mirror with one hand on her boob and the other between her legs, and she blushed a little at how horny and weird her fantasies had just been. So, to answer his question: being a girl, or at least this part of it, felt really good. Also, it seemed to have made her attracted to guys- when she thought about sex, her mind still went to cocks and having them fuck her.
She wondered what to do with her newly transformed body...