Mirai is a first-year high school student with the ability to manipulate blood, an ability that is unique even in the spirit world. This ability causes her to be isolated, leading her to jump off the roof of the high school until she is saved by Akihito.
Clumsy and a bit aloof, Mirai rarely stands out in school. In fact, she struggles pretty much in life; she has to earn her own money to make ends meet, but her constant fear of actually encountering a youmu prevents her from earning an income from slaying youmu, which most spirit world warriors take on as part of their profession. To make things worse, her hobby of writing blog articles about bonsai is often ridiculed on the Internet.