X-Change

X-Change is a Japanese eroge produced by Crowd and distributed in English by Peach Princess. A remake of the game, X-Change R was later produced by Crowd, but Peach Princess has stated they do not intend to market this game. However there is a collection of x-change(the first three) released by jast usa which adds stuff from the R releases of the first game(not two unfortunately) and has the third one and translates them.

Plot
What would you do if you were a man who suddenly turned into a woman? It'd be a great experience, and you'd probably make some interesting observations.

You are Takuya Aihara, an average junior college student with one character flaw: you're a bit of a mental weakling. No matter how hard you try, it seems that all the girls around you are constantly pushing you around: your teasing step-sister Natsumi, the genius president of your chemistry club Asami, but especially Asuka, your beautiful childhood friend.

One fateful day, while cleaning some shelves in the chemistry room, you spill a mysterious chemical on yourself. The next thing you know, you've been transformed into a girl! And so begins this hilarious erotic adventure. As a woman, you discover a new world of experiences, some welcome and others not. Can female-Takuya find a way back to normal, while avoiding the many temptations that come with his new female body? Can he find a way to express his feelings for Asuka, without hurting another who lives him?

Characters

 * Takuya Aihara (相原拓也/たくや?) : The Main Character. He turns into a female by spilling a mysterious chemical on himself.
 * Asuka Katakiri (片桐明日香?) : A close friend of Takuya. Takuya has secretly been in love with her since childhood.
 * Asami Satoh (佐藤麻美?) : The president of the science club, of which she and Takuya are the only members. Though very smart, she is also somewhat unscrupulous in experimenting on Takuya.
 * Professor Miyagi: The art teacher at Takuya's school. He is extremely kind and he gets along well with the students. Miyagi doesn't treat Takuya any differently after Takuya becomes a female by the accident.
 * Nurse Keiko Matsunaga (松永啓子?) : The school nurse. Most of the male students are smitten with her, enough though there have been rumors about her private practices in the nurse's office.
 * Mr. Terada: The gym teacher, who was hard on the weak Takuya and is even harder in a different way when Takuya becomes a girl.
 * Natsumi (相原夏美?) : Takuya's older stepsister. She is controlling and always demands for things to go her way. She often abuses Takuya, the degree of which increases in the third game.
 * Seiji (清次?) : Natsumi's boyfriend, who shows an interest in the female Takuya.
 * Koji Kudo (工藤弘二?) : Being very shy, he doesn't have many friends. Strangely, he has fallen for the new Takuya who takes his virginity.