Originating from Touhou Project's "Embodiment of Scarlet Devil", Rumia is a blonde, red-eyed youkai resembling a human girl with no additional features, but her hair and skin are photosensitive. Living in Gensokyo, she's supposed to hunt humans, but she's lazy, sometimes not as committed to the job. She's usually flying around Gensokyo enveloped in a sphere of darkness, wandering to find whatever of interest goes on. Rumia isn't all that smart, though she tries to understand where she can.