Family name O-Oka (O-Oka 
) , in the entire world, is an extremely rare cognomen. The last name O-Oka is characteristic of Northern America, particularly the United States, where it is an extremely rare surname. Parts of the name also exists independently as a last name O, and a last name Oka.
| VARIANT | COUNTRY |
|---|---|
| O-Oka | United States |