Family name Исои (Исои 
, Isoi 
) , in all the world, is a very rare last name. The last name Исои is habitual in Russia, where it is an extremely rare surname, Germany, and the United Kingdom. Measured by absolute frequency, it most frequently occurs in Russia, Germany, and the United States. Also, Исои is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Исои | Russia |
| Isoi | United Kingdom, Russia, India, Germany, United States |