“There is a girl who is the last surviving member of a ‘certain clan’ and a ‘half-youmu’ boy who shouldn’t exist...
This is their story.
One day after school, the half-youmu boy, Akihito Kanbara, meets a girl who looks as though she is about to jump off the roof at any second. Her name is Mirai Kuriyama. She is the last surviving member of a clan that has a blood curse that is unique even amongst the Under World Warriors.
An unchanging room. An unchanging lifestyle. An unchanging world. That was how his days were supposed to be.
Yet, the moment that girl survivor met the half-youmu boy, his world changed completely.”