A search through an extensive database of Japanese female names turned up one Aisato, written 愛沙都 ("love" + "100 millionth" [used as a phonetic] + "capital city"). So while there is apparently at least one Japanese person with this name, it is exceedingly rare. (The same source listed 30 different kanji combinations for the name "Aisa.") For Aisato, I feel sure that the previously mentioned West African origin is the correct one in this case.
This message was edited 10/9/2017, 5:49 PM