Tsuki ha Higashi ni Hi ha Nishi ni: Operation Sanctuary

Naoki Kuzumi is a high school junior who lost his parents in an accident five years ago and now lives with his aunt, uncle, and cousin Matsuri. His life seems ordinary, except for the gaps in his childhood memories. One day, as he naps on a bench, a redheaded girl named Mikoto suddenly falls from the sky onto him. Strangely, she believes he is her younger brother. Naoki's present time serves as a refuge for people from the future, where a deadly disease is spreading. When Mikoto learned her brother Yuusuke had been sent to Naoki's era, she traveled back in time to find him.