Zhou Mi once said: "When I first got to know Sungmin hyung, I thought that he must be really young, and so very caring/kind, like a little brother. He was easy to be with, so I didn't speak to him using formalities. It was until SJ-M was about to debut, once I heard that Siwon calling Sungmin 'hyung', I was so shocked and asked 'Sungmin is a hyung?!'. Siwon stared at me and said 'Of course, what did you think?'. Immediately I went over to Sungmin said 'hyung I'm so sorry! I have been speaking to you so informally for the past year!!'. Sungmin hyung smiled and said it was fine! n__n