Also a student of Miyasaka High despite her age, Mirai is a lightning demon that takes on the form of a cute, 14-year old bishōjo. Initially tasked to kill Gekkou, she later went on to form a contract with him. While she is considered to be an upper-class demon of noble blood, most of her powers are usually sealed away by Gekkou and can only be re-activated with his permission, upon which her hair will turn golden and her body will be wrapped in a vortex of lightning. She is described to be excessively boisterous and annoying to Gekkou, though on the flip side, she is often irritated by Gekkou's apparent indifference to her existence. Her favorite pastime is reading manga and drawing.