Finally we have an article about this issue posted in Allkpop.
Way before the song was released, the teaser lyrics of the new Homin’s song was caussing a fuss in Korea, alot korean netizens were talking, majorly because It’s seems Homin/SM are dissing JYJ, not only netizens are talking also journalists and singers, most of them are bad reviews, SM says” The song is an expression of love and heartbreak between two lovers” but korean cassies say that line “Keep your head down” is to diss rivals, never used to a love relationship. One famous and respectable korean singer Jo-pd openly talked
“wow new TVXQ music is F* shit ‘why u left me so easy, Keep ue head down’ sme/hm r together sharpening knife, when smp become hiphop?”
A korean cassie also explains to international fans the real meaning:
“In Korea, when someone ignores and looks down the others, we use expression like this, ‘keep your head down’. It’s really vulgar expression”
Read the lyrics by yourself, the rap part done by Yunho is the part who cause alot fuss.