In the distant future, humanity has terraformed Mars into an oceanic world to meet their needs. Now called Aqua, the planet serves as a new home for those dissatisfied with life on Manhome—the planet formerly known as Earth. As a perfect replica of Manhome's Venice, the town of Neo-Venezia has inherited all the rustic charm of the original. Gondolas navigate the waterways of the dreamy town, while nostalgic alleys await those who travel on foot. Akari Mizunashi, a young native of Manhome, has recently made Neo-Venezia her new home. To pursue her dream of becoming a gondolier tour guide—or Undine—Akari joins the Aria Company, one of the most renowned water guide companies in town. As she enjoys a simple lifestyle unavailable on Manhome, Akari cheerfully wanders through her daily life in Neo-Venezia: a town where magic and miracles abound.