Shiranui

At the end of the summer vacation, Hayate, Nagi, and company take a trip to the countryside; a place with no games, no anime, and no mobile signal. ~ translated and adapted from official site by Cranston

Sanzen'in Nagi invites all her friends to the private beach inside the vast Sanzen'in estate. Just as Nagi is about to join in the fun, a vengeful spirit intent on disrupting their fun appears.

In the era of the gods, year 300: Yuuna Yuuki lives an ordinary life as a second-year middle school student, but she is also a member of the Hero Club, where club activities involve dealing with a mysterious being called Vertex. Source: ANN