"It's summer. The place is a crater lake near the naturally ambient, rural village "Takachiho". The protagonist is standing still, blankly looking at the far-away sky. Amnesia... His memories of the past have been lost. It's a strange thought, but to him on that day, the sky seems tailored to both dusk and sunrise, a mysterious color..." The protagonist, Aisa Ryu was a freeloader in a house, living there with four beautiful sisters. Until suddenly, one day, a sad incident occurred...