Surname 昌久 (Changjiu 
, 昌久 , Masahisa 
) , in the world, is a rare family name. The family name 昌久 is habitual in Japan, where it is a rare surname, China, where it is a very rare surname, and Chile, where it is an extremely rare surname. More frequently, 昌久 is the forename as well as the last name.