We remember gen3/4.
We see a young Mirun-chan striking a difficult pose in a game of freeze, whilst Mai-chan addresses the camera. Mirun-chan's poise fails her, and her pose is lost. Her audacious attempt has failed, but the other girls remain frozen until Mirun-chan playfully disrupts Yuuna with a push. We see the bond between Mirun-chan and Yuuna runs deep. We are not sure whether the shy Mirun-chan would push the other two girls in the same way she pushed Yuuna. These were the formative days of the Axis of Purity.