Yosuga no Sora: In Solitude, Where We Are Least Alone.

Haruka Kasugano and his twin sister Sora have lost both their parents in an accident, and with them all their support. They decide to move out of the city to the rural town where they once spent summers with their late grandfather. At first everything seems familiar and peaceful, but changes come as Haruka starts to remember things from his youth.

(Source: Anime News Network)