She's not from an anime. She's from the Touhou Project bullet hell danmaku series first created in 1996 but not popularized until around August 11, 2002. She first appeared as a the stage 5 boss in the 8th game, Imperishable Night. She has the power of manipulating insanity and wavelengths with her eyes, hints the name of her theme, Lunatic Eyes ~ Invisible Full Moon. She's a medicine student of Eirin Yagokoro, a ware peddler, and seen as sort of a pet by Princess Kaguya Houraisan. But it's all right that you thought she wan an anime character! It's a very common mistake that almost no Touhou fans mind! There's also another version of her, Rei'sen/Reisen Inaba/Reisen II/Reisen III. They're almost the same person, but Rei'sen has different hair, and she's a soldier.