It sells itself as an alien-invasion horror story and then spends thirteen episodes quietly breaking your heart in a girls' boarding school instead. Mari Wakatake arrives loud, furious and amnesiac, picks a fight with the cold, perfect Hagino Senkouji, and neither of them knows how to hold the fact that Hagino commanded the Arume ship that emptied Kamioki Island of everyone Mari ever knew. Watching Hagino try to be a normal student, with Tsubael hovering at her shoulder, is the show's cruelest trick: you start rooting for something that can only end one way. Akihito Yoshitomi's premise gives you an all-female species from the stars, but the actual weapon is silence, all those pauses where somebody nearly says the true thing and doesn't. It looks like a slow, dated little 2007 series until the last stretch takes your legs out. Then the ending arrives, and you sit there for a while.
Mari wakes with no memory of the catastrophe that killed everyone on Kamioki Island five years ago. She's the sole human survivor, though she can't remember why or how. Now trapped at Kaihou Academy, an elite girls' school isolated from the outside world, Mari begins to sense that her presence here is no accident. Someone is watching her, waiting for her memories to surface. What she doesn't know is far worse: she may not have been the only thing that walked away from that island alive. When a mysterious girl named Hagino transfers to the academy, Mari feels an immediate, magnetic pull toward her. But intuition screams that Hagino cannot be trusted. As strange events unfold and Mari's fractured memories begin to surface, the line between protector and threat blurs. Something inhuman wears a human face at Kaihou Academy, and Mari holds the only key to understanding what it wants. The question isn't just what happened five years ago, but whether Mari can survive learning the answer.