You was at a Live Show that was being performed for the Celebration of the Anime Show 'Haitai Nanafa'

Two Hosts came on stage alongside a Staff Member dressed up as one of the Characters: Yumi Igarashi. She waved cutely at the Crowd as her giant head moved around

Host #1 spoke in Japanese "Hello Everyone, thank you all for coming to our Live Show, we hope you enjoy our Dance Number!"