Surname Oyasan (Oyasan 
) , in all the world, is a rare cognomen. The family name Oyasan is characteristic of Philippines, where it is a very rare surname, Malaysia, and the United States, where it is an extremely rare surname. Measured by absolute frequency, it is the most numerous in Philippines, Malaysia, and India. More prevalently, Oyasan is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Oyasan | Philippines, Japan, India, Malaysia, United States |