Family name Sadayasu (Sadayasu 
, Огасавара 
) , in all the world, is a very rare last name. The family name Sadayasu is characteristic of Singapore, where it is a very rare surname, the United States, where it is an extremely rare surname, and China.
| VARIANT | COUNTRY |
|---|---|
| Sadayasu | Singapore, China, United States |
| Огасавара | Russia |
| sadayasu fujii (b. 1945) |
|