Origin: Russian, Irish, Japanese
Meaning: the Russian feminine form of Cyrus, which is the Greek form of Kyros from Persian Kurush meaning "far-sighted" or "young". It has also been associated with Greek kyrios meaning "lord".
Kira could also be the feminine form of Kir, a Russian masculine name meaning "master, ruler" so Kira could translate to "mistress, ruler".
It could also e a variant spelling of Ciara, an Irish feminine form of Ciar meaning "black".
Kira also seems to be a Japanese unisex name, as well as a surname, though I couldn't find a specific meaning behind the name. The term kira kira means "glittery, shiny" in Japanese.