After losing their parents in an accident, Haruka and Sora, his younger sister, move to the town where their grandfather lived. They visited his house many times when they were kids and they still remember it. Nao, their old friend, Ryouhei, his classmate, Akira, a miko at a neighboring shrine, and Kazuha, Akira's close friend, welcome them. Nothing has changed. The good old memories and silent atmosphere heal Haruka's sadness. However, his peaceful life gradually changes. A secret promise made long time ago. A lost treasure. The real reason for moving to the town. The story now starts under the summer sun... (Source: erogeshop, edited)

Yosuga no Sora is based on the 2008 visual novel of the same title.