Long ago, demon-like creatures known as Oni butchered humans and brought on destruction solely for their own delight. A lone man named Momotarou opposed these gruesome, near-invincible monsters, but the war against them was just beginning. Thousands of years in the future, temperamental gun enthusiast Shiki Ichinose leads a carefree life. However, after his expulsion from school, everything changes. Shiki is suddenly...