This is the song that first made them famous. It’s called Replay now, but initially it was Noona You’re So Pretty. Noona means older sister, a woman you admire, that is older.
They will show clips of when they were all much younger and just beginning with this song. Taemin was only 16 years old, at the time. The oldest, Onew, was around 19 years old.
Again, this is sung in Japanese at the Toyko Dome.