Cognomen Тадао (Tadao 
, Тадао 
) , worldwide, is quite a rare family name. The last name Тадао is characteristic of Japan, where it is quite a rare surname, Hong Kong, where it is a rare surname, and Philippines. In absolute terms, it is commonest in Japan, Philippines, and China. Much less frequently, Тадао is the forename as well as the last name.