Blue Drop: Tenshi-tachi no Gikyoku

Synopsis

Mari Wakatake is sent by her grandmother to the Kaihō Academy, with Mari resentful at her enrollment. On the way, she sees a girl standing on a rock surrounded by birds. At the school, she meets the headmaster, and is subsequently shown around the school by Michiko Kōzuki, a student. The headmaster learns from Mari's attorney that Mari lost her memories after an incident in Kamioki Island five years prior. In her dorm, Mari is greeted by Hiroko Funatsumaru, the dorm leader, Hagino Senkouji, who after shaking her hand, starts choking Mari, her eyes turning blue in the process. She relents and Mari furiously runs out the door. She is later comforted by Michiko, who recommends that Mari get to know Hagino. At dinner, however, Mari attacks Hagino, and during the night, follows Hagino outside, where a giant alien ship rises from the water.

(Source: Wikipedia)