I think this name is beautiful! I am currently studying Japanese and I think I might use this as my Japanese name, as I was born on a day of a full moon :) I also have always felt a strong connection to the moon and I think this name is very pretty!
Because the name "Tsukiko" means moon child, it would fit best to a girl born under the zodiac sign Cancer, because of Cancer's ruling planet, the Moon. This name can be used however people choose it to be used though. I wish this was my name, because I was born under Cancer. I really love this name.