A carnivorous youkai with the ability to manipulate darkness when attacking humans. She dislikes sunlight, concealing herself in darkness to protect herself, but ends up impairing her own vision, leading her to be portrayed as a member of Team 9, a posse of childish low-tier Touhou characters. She is also portrayed in her "crucifixion" pose, and is best known for her catchphrase: "そーなのかー?" ("So-nanoka~?" - "Is that so~?"). The pixiv tag 毎月七日はルーミアの日 ("Maitsuki nanoka ha Rumia no hi" - "The seventh of every month is Rumia day") is a pun off of her catchphrase, since "nanoka" can also mean "七日" ("seventh day").
Fandom created an alternate form which can be triggered if her ribbon be removed. This spurred from speculation on why Rumia couldn't remove or touch the ribbon.
On occasion, she is depicted completely surrounded by darkness, flying around as a solid black sphere with only the presence of her catchphrase or her ribbon sticking out from the darkness identifying her.
Person: blonde hair, red_eyes
Outfit: bow, hair_bow, hair_ribbon, ribbon, skirt, vest, blouse, wing_collar, black_skirt, white_blouse, red_ribbon, red_bow, necktie, red_neckwear, white_shirt, bowtie, cravat, mary_janes, red footwear, long_sleeves, socks, dress_shirt
Other: outstretched arms, floating, flying,