Top 13 in Top 20 best Gender Bender comics should not be missed.
For the treatment of his beloved sister, Shinomiya Ryouma is working frantically to earn a billion yen while going to high school. One day, a mysterious woman asked him, "Can you lead your life to what you desire?" And after getting a ticket from her, an accident happens to him! When he wakes up, he finds he's turned into a girl and what's more, he's engaged in a "game" where a win means he can reverse his fate but lose nothing. which means you will die instantly!