Star Signs are pictures or symbols that represent a birth date from a fraction of a month to another. Star Signs would be commonly used in New Leaf in a Town Pass Card, in the section where the mayor's birthdate would be in.
There is also furniture that was distributed only for the Japanese version of Animal Crossing: New Leaf as DLC from early December 2013 - late November 2014. The items would be distributed through the months that the star signs would be enlisted in
amiibo Card Gallery