Surname Kōsuke (Kosuke 
, コウスケ , Kōsuke) , in the world, is a common last name. The last name Kōsuke is habitual in Japan, where it is quite a common surname, Singapore, where it is a rare surname, and Indonesia, where it is a very rare surname. In absolute terms, it is commonest in Japan, China, and Indonesia. Very seldom, Kōsuke is the forename as well as the last name.