A Nijiura Maid who is typically invisible.
Though it's tempting, please do not tag her in every Nijiura Maid image just because she is invisible. Usually, there will be signs of her presence (like a bowl with seemingly no one at it, or just a shadow.) When she appears, she has long black hair and wears a (typically green) camo maid uniform.
Her name comes from inai - "not here."