As you already know, Tae-yeon from SNSD stars as Kaoru in the Korean musical version of Midnight Sun. Some audio and video has started to show up on YouTube and in the clip below you can hear (no video) Tae-yeon sing a Korean version of Good-bye days.
She sings very well and the Korean version is nice. But I had expected them to have original music in the musical, not just Korean versions of YUI’s songs
They do, of course, have other songs too:
I would like to see this musical so badly!