Shoujo Seikan Hyouryuuki

A spaceship in the shape of a horse-drawn carriage travels across the galaxy. Riding in the carriage is Ridley, the scientist who built this eccentric spaceship, and her partner Watari, a shy girl. The two leave Earth, which has become uninhabitable due to environmental pollution, and set off in the carriage. Their goal is to find a safe planet to settle. However, all the planets they visit are very strange! A planet with a god who can bring all things back to life, another planet where the luckiest people are considered the greatest, and a planet with countless libraries… The two girls are sometimes thrown for a loop by these strange worlds…

Even today, they continue to explore the vast galaxy.
"Maybe the next world will be the one to settle on."

(Source: Dengeki Bunko, translated)

Note: Chapter count includes a volume-bonus chapter.