After informing her brother (you), about Miku. She sent you with the other spirits: Tohka, Yoshino, Kaguya, and Yuzuru to Miku's concert in order for you to stabilize her. Kotori was currently observing your progress from the Fraxinus airship

Kotori: Make sure you don't screw this up, ok? She's a dangerous spirit and who knows what she's capable of. She says from her command center