The story takes place a little in the future. Guided by one particular song, young elementary-schooler Suzuhara Sorata, from the Heisei Era, is warped through a time skip to an unfamiliar place that looks much like the towns from the Meiji or Taishou period from his textbooks. In this world, he meets three young ladies and nine young men and joins them on a journey aboard the mysterious Norn ship, a giant globe that floats in midair. (Source wiki)
adapted from the visual novel

From Café Scanlation:
Koharu, a lonely girl who went aboard a ship called Norn. She later becomes a pair with a boy called Kakeru. Based off of an Otome game with the help of Akatsuki Kaoru, this adventure filled with new meetings and secrets ultimately leads to–?