As a duty of the Disciplinary Committee, Yuki and Zero must conduct a surprise inspection of the students' belongings at both the Sun and the Moon Dormitories. Just as they are about to enter the Moon Dormitory, Zero suddenly leaves the school grounds. Yuki goes after him in a panic but can't find him. As she roams the streets by herself, Yuki is haunted by her memories from ten years ago, when suddenly a mysterious mother and child appear before her.

A new ethics teacher, Toga Yagari, arrives at Cross Academy. His looks, which are atypical for a teacher, are all the buzz among the Day Class students, and even Zero seems to have lost his usual composure.