Actor Kim Dae-myung revealed what actor Lee Kwang Soo's personality is like in real life. 

On August 16 episode of SBS' television show 'Running Man', Kim Dae-myung made a guest appearance. 
During the opening, Kim Dae-myung mentioned featuring on a web-drama 'The Sound of Your Heart' with Lee Kwang Soo in 2016. 

Kim Dae-myung said, "Kwang Soo is very polite. He is really nice to everyone. But when I see him on 'Running Man', he's so different." 

As soon as Kim Dae-myung said this, the 'Running Man' cast burst into laughter. 
Then, Kim Jong-kook playfully commented, "Kwang Soo is pretty much insane when he's here with us." 

In response to this, Yu Jae Seok said, "Well, you always say that everyone apart from you are insane here." 
 
(Credit= SBS Running Man) 

(SBS Star)