A moon rabbit, she came to Gensokyo about 30 years ago to escape a war between the Earth and the Moon. Since then, she has been an apprentice to Eirin, a pet to Kaguya, and a caretaker to Tewi. She has the power to drive people mad with her eyes—mainly in the form of hallucinations—as well as communicate telepathically with her kind. She also has control over waves of all kinds, such as light waves, brainwaves, and electromagnetic waves. "Udongein" and "Inaba" are both nicknames, the first given her by Eirin and the second Kaguya; the latter is what Kaguya calls all rabbits.

(Source: Wikipedia)