Across the world, 洋一郎 (洋一郎 
) is a very rare boy's given name. The forename 洋一郎 is habitual in Eastern Asia, particularly China, where it is an extremely rare male name. Very seldom, 洋一郎 is the last name as well as the forename.
| VARIANT | COUNTRY |
|---|---|
| 洋一郎 | China |