Cognomen Sejin (세진 
, 色堇 
, Sejin 
) , in the world, is quite a rare last name. The last name Sejin is habitual in South Korea, where it is quite a rare surname, Colombia, where it is a rare surname, and Australia, where it is a very rare surname. Not in comparison with a country's population, it is the most numerous in South Korea, Colombia, and China. More frequently, Sejin is the forename as well as the last name.