In addition to her song of confusion, she can make people night-blind.
Humans call her the Night Sparrow, but few have ever seen her appearance. This is because she only plays during nighttime, and humans around her become blinded by darkness anyway. Had they seen what she actually looks like, they probably wouldn't have called her a sparrow.
Her song can cloud a person's judgment; humans who walk into the night in that condition inevitably disappear without a trace. This confusion ability is the main reason people lose their way at night so easily.
She can also make people night-blind in order to hide better within the darkness.
(From Touhou Wiki)