Last name コイン (Coin 
, Coyne , コイン 
) , in the world, is a common surname. The surname コイン is habitual in Ireland, where it is quite a common surname, Australia, where it is quite a rare surname, and the United Kingdom. In absolute terms, it is the most numerous in the United States, the United Kingdom, and Ireland. Much less frequently, コイン is the forename as well as the last name.