Singer Kim Bum Soo revealed his abs.

On September 25, Kim Bum Soo posted on her Twitter, "Coach Yang who allowed the ballad king of Korea to take off his shirt.. Thank you so much~ Even though I couldn't overcome my short proportions, this is great progress, right?" along with two pictures.

In the pictures, Kim Bum Soo is posing for the camera with his personal trainer or is looking down at his abs with his shirt off.

Internet users who saw this commented, "Wow, his abs," "Yes you're right," etc.

Kim bum Soo released a new digital single on September 23.