About Yu-No: A Girl Who Chants Love At The Bound Of This World

One day, you suddenly received a package from your father, who was supposed to be dead 3 monthes ago in a archaeological reserch. You opened the package and found a strange device and a letter without date: "Take this to the Triangle Cape tonight... "
You felt strange but still went to the Triangle Cape, supposing that the "tonight" on the letter means this night, and then, the reality changed...