While visiting a store in Landosol, Yuuki and Kokkoro encounter Aoi wearing an unfamiliar uniform. It turns out that Aoi is a new student at the prestigious St. Theresa's Academy for Girls, but is worried she won't be able to fit in. Thus Yuuki and Kokkoro head to the school with her as moral support.

Kokkoro arrives at the post office to send a letter, where she is unfortunate enough to encounter a group of robbers who have broken in. In order to recover their stolen letters, Kokkoro joins forces with two Lucent Academy students named Suzuna and Misaki to pursue the thieves all the way to their hideout...