After a Momotaro assassin suddenly kills his adoptive father, Shiki vows to avenge him. But first, he must learn to control his newly awakened Oni blood.

Hatori Chise, 15 years old. Lost, without hope and without family - she sells herself to a non-human mage known as Elias Ainsworth. Hesitant, she starts a new life with him as his new apprentice.

Inside a vast, self-replicating city bent on eliminating all life, mysterious loner Killy emerges to guide a remnant of humanity desperate to survive.