Takayama's friend, Mari SasshÅ, works in a restaurant near the defense headquarters. While eating lunch, she serves them and is introduced to everyone. She will also be attending the same Academy. The next day, SasshÅ's friend Kaori goes missing and she requests the Defense Four's help finding her. They go through reports to no success and SasshÅ ends up hearing Kaori's phone ringtone in the lost and found...