In a world where supernatural beings known as youmu are hunted by Spirit World Warriors, Akihito lives an eventful life. He’s a half-breed from a human mother and a youmu father, and is immortal - a fact that saves his life on a regular basis, for his bespectacled classmate Mirai can’t seem to stop stabbing him in the chest. She’s a Spirit World Warrior with the power to control her blood, which she manifests into a sword; and with low self esteem about her abilities to hunt youmu, Mirai constantly uses Akihito as target practice. In hopes of being left alone, Akihito must now help Mirai gain confidence to take down sinister youmu.