A line that displays Miyu’s position towards the Class Cards. One could think that the Cards flew to the Mirror World together with her as an after-effect of her transfer. Miyu herself immediately realized that probability. From the timing at which Rin and Luvia (or rather, the Mage Association) moved, it seems a slight miscalculation occurred between the timing of appearance of Miyu and the Cards.
I Must Do the Cleaning Up