He'll be releasing an album called 'Musical December 2013 with Kim Junsu' for the musical next week, but he's giving you a taste with a duet with the talented Lyn called "Brushing By". 

A rep previously raised anticipation for the release, commenting, "Junsu will be the first Korean singer to release an album full of newly edited songs instead of the the original musical OSTs. Please look forward to how the skillful Junsu interpreted his songs."