Kousei Arima was a genius pianist until his mother's sudden death took away his ability to play. Each day was dull for Kousei. But, then he meets a violinist named Kaori Miyazono who has an eccentric playing style. Can the heartfelt sounds of the girl's violin lead the boy to play the piano again?

For years, a great war has raged on between the scientifically advanced Empire and a paradise of witches known as the Nebulis Sovereignty. This age-old battle sets the scene for a fateful encounter between two young combatants: an imperial swordsman, Iska, and the witch princess, Aliceliese. As sworn enemies, they vow to cut each other down in order to unite their worlds, and yet Iska finds himself entranced by her beauty and righteousness, while Aliceliese is moved by his strength and resolve. In the midst of a never-ending war that forbids them from being together, they have no choice but to destroy each other-or find another way.