Sailor Suit and Alien (Serafuku to Uchujin)

When Kibou Minase wakes up, she finds herself wearing a sailor suit and lying in a white room. She is in a spaceship. Planet Earth was hit by a meteorite and all living creates perished except for 11 people who were saved by an alien. Those saved include a man who claims to be part of the Earth Defense Force, a pilot who can't speak, a pregnant woman and elementary school student. Those left are faced with the choice of living with aliens in a faraway place or escape the spaceship and build a new city on Earth.