He started to use the stage name Yoo Ah-In when making his debut in a TV commercial. His first management wanted to create a pretty stage name for him that fitted an idol image because his name Uhm Hong-Shik was considered too heavy, old-fashioned, and not refreshing sound for celebrity name. So his manager encouraged him to change his name, and he chose the name Yoo Ah-In. The 'Ah-In' part was taken from German word 'ein', means 'one', which implies he is a unique being.
