BLUE DROP: Tenshi-tachi no Gikyoku

Five years ago, a catastrophic event occurred on Kamioki Island, erasing Mari Wakatake's memories while killing everyone else. Now attending a secluded girls' academy, Mari is being observed, as those watching believe her memory will eventually return. A disturbing possibility exists that she was not the only survivor. As an unknown presence in a female form infiltrates the academy, Mari finds herself drawn to a mysterious girl who may be key to her situation, though she cannot fully trust her.