Japari Park is an enormous integrated zoo built somewhere in this world. A mysterious substance found there, called "Sand Star," causes the animals to turn into humanoid beings called "Animal Girls"! These new creatures spend every day peacefully with the zoo's visitors... but after some time, a lost child turns up in the park. The child's attempt to find the way home turns into a great adventure with the Animal Girls!

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.