Utsusemi ni Fureru Mono

Kanata is an ordinary university student. He lives a peaceful life in a small town. But, everything in this world has two different sides like day and night, front and back, and light and darkness. The monsters in the darkness and the monster busters, Yoshino and Sherlot. Kanata gets involved in their battle by chance, and he is captured by the queen of the darkness, Beatrice. She tells him, "I need your power." What will happen to Kanata in the end...?