Family name Ounaga (Ounaga 
) , globally, is a rare cognomen. The cognomen Ounaga is habitual in Japan, where it is a rare surname, and Brazil, where it is an extremely rare surname. Very seldom, Ounaga is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Ounaga | Japan, Brazil |
Toyoco, and Katsuratsukasa