D.O was a trainee of Exo. Luna was a trainee of f(x).    Exo was practicing Mama in their practice room.   F(x) was practicing Electric Shock in their practice room.  

It was winter time, when Kyungsoo finally felt warm. And his coworkers know it.  

Luna and Kyungsoo first met in a dream. It was made possible by the Red Strings or Strings of Fate wherein two people who slept at the exact same time will be able to talk to each other through their fantasies. They both thought that it was a just a mere coincidence on why they continuously find each other on dreamland and neither of the two believed that one of them existed in real