In this world, creatures like vampires and werewolves still walk about, but Aya Rindo can’t say the same for herself. This beautiful disembodied head, carried by her maid Shizuku Hasei, is a detective in search of her stolen body. One evening, they meet half-human oni slayer Tsugaru Shunichi, who offers a lending hand. Now, the trio is traveling through Europe, solving mysteries along the way.