For his beloved younger sister\'s treatment, Shinomiya Ryouma is working frantically to raise a billion yen while going to high school. One day, a mysterious woman asks him, \"Can you put your life on the line for what you desire?\" and after receiving a ticket from her, an accident befalls him! When he wakes up, he finds he\'s turned into a girl and what\'s more, he\'s participating in a \"game\" where a win means he can reverse his fate but a loss means he\'ll die instantly! (Euthrosyne)