Tenri, Keima's childhood friend, has moved back next door to the Katsuragis.  She happens to be host to the goddess Diana, who tells Keima about she and the other 5 Jupiter Sisters once sealed away the Ancient Demons of Hell, the Weiss.  At the same time, the students of Maijima High School are excited because Kanon has made a rare appearance in the classroom for exams.  However, Kanon is preoccupied with the girl inside the mirror named Apollo, as well as the fact that she is being watched.
Hmm?