my adopted sister’s birth certificate

My sister was born 2/2/61 in shuri city, Okinawa and was adopted by my dad who was in the marine corporation stationed on Okinawa at the time. We are searching for any record of birth for my sister who resides in the U.S. currently. All my father had was a document, drawnup by a Japanese legal firm, affirming her adoption. For legal reasons here in the states, she needs a copy of her birth certificate.please tell me how to go about this

Mr. Richards,

In 1961, Okinawa was occupied by the U.S. and there was no Shuri city, but if your sister was born a Japanese, perhaps you can start by either contacting your local Japanese Embassy or Naha City where Shuri district lies. The email address for Naha city hall is;
neo.city.naha.okinawa.jp