Tsuki wa Higashi ni Hi wa Nishi ni: Operation Sanctuary OVA
Japanese title: 月は東に日は西に〜Operation Sanctuary〜 OVA
Alternative titles: Hani Hani: Operation Sanctuary OVA, The Moon is East, The Sun is West: Operation Sanctuary OVA
Type: OVA
Source: Visual novel
Episodes: 4
Status: Finished Airing
Aired: Dec 12, 2004
Duration: 12 min per ep
Rating: PG-13 - Teens 13 or older
Studios: Radix
Genres: Comedy, Drama, Romance, Sci-Fi
Themes: Harem, Time Travel

Naoki Kazumi's parents died in an accident and since he had nowhere to go, he now is living with his cousin Matsuri Shibugaki. One day up on the school's rooftop a girl falls out from the sky. The girl is called Mikoto Amagasaki, and she comes from 100 years in the future,  she went back in time with hope to eventually find her missing brother. However , when Mikoto sees Naoki, she end up mistaking him for her brother.

(Source: Wikipedia)