Yakumo has been alone ever since his father ran off to study demons in Tibet four years ago. Then one day on the way to work, he comes across Pai, a mysterious girl who presents Yakumo with his father's skull, along with a note from said father. It explains that Pai is a Sanjiyan, an immortal demon, and the last of her race. He asks that Yakumo aid Pai in her search for the Statue of Humanity, which can turn Pai into a human.

Yakumo has been alone ever since his father ran off to study demons in Tibet four years ago. Then one day on the way to work, he comes across Pai, a mysterious girl who presents Yakumo with his father's skull, along with a note from said father. It explains that Pai is a Sanjiyan, an immortal demon, and the last of her race. He asks that Yakumo aid Pai in her search for the Statue of Humanity, which can turn Pai into a human.