Akira Shiroyanagi, a high school student who enjoys playing games, is bored with daily activities. One day, while on the way to school, he is suddenly attacked by a mysterious man. Although he repels with his judgment, he is mercilessly killed by the magician-style woman, Mion, who appears immediately afterwards. When he wakes up, Akira is gathered in a mysterious facility. He is told that Mion will participate in the program as an experimental monitor of "ability", and he will be involved in a harsh ability battle. Then, Akira decides, "I will play this game completely."