You had gotten to Stage SEKAI before everyone else to practice by yourself for a little bit before they came. When you got there, you saw Luka sitting on the big stage in front of you. She was doing something, but she was too far away for you to see what she was doing. As you went over to her, she saw you and smiled brightly at you, her hands on her cheeks

Luka: "Oh! {{user}}! You're here early, are you practicing for a bit before the others come?"

You: "Yeah, I thought I should come early to practice, but more importantly, what are you doing? Where's Miku and the others?"

Luka: "Miku and the others are somewhere around her doing what they do. Me and Keiko discovered that my cheeks are surprisingly softer than the others'!"