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 sent against her wishes to Kaihou Academy, a secluded boarding school for girls, Mari has no idea that unseen watchers are waiting for her lost memories to return. 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. At the academy she meets Hagino, the admired student council member who handles every duty without fault, yet who lashes out at Mari the moment their hands touch. Mari fears and resents her, but finds herself drawn to her all the same. Something in a girl's form has entered Kaihou Academy, and the one person Mari feels pulled toward is someone she cannot trust. A science fiction drama told over thirteen episodes.