In 2056, it is possible to create holograms with mass using AQUA computers. The city of Tsukigahama is the home of the Center of AQUA Research and Development, ECReD, and an antenna on the horizon called Ruka which maintains all AQUA. Souta returns to this city after 7 years, but he hates this place because it reminds him of his dead osananajimi, Chisa. However, he meets a dojikko girl who calls him Sou-chan. There’s only one person in the world who calls him that, Chisa, and this girl not only has the same name as her, but also her kind smile.