AIKa ZERO

19-year-old Aika reunites with Eri and Karen to investigate the serial disappearances of school girls at St. Aero academy. Some of the girls have returned but without any memories of what has happened. While going undercover as students, they discover that the student council group called the White Knights have been abducting the students, and that they are in cahoots with an alien force that penetrates and captures the girls using rope-like tendrils of light. Aika is captured by the alien, but is rescued by Risako.

Miyu's back story is expanded upon regarding how she encountered the aliens and then influences her classmates to join her in the student council. The army takes over responsibility for the investigation. When Karen goes in undercover, she notices the council has deserted the chapel. Meanwhile, the Hagens have been observing their actions. When the White Knights capture more girls, Aika raids the underground.