YU-NO: A Girl Who Chants Love at the Bound of This World

Takuya Arima is a high school student who enjoys every day of his life. His father is a renowned researcher who has been studying parallel worlds: he is convinced they exist and that it is possible to travel between them. Then one day his father disappears without a trace, to the shock of everyone close to him. Takuya takes the loss hard, with no idea of what he is about to face. During the summer vacation he receives a package from his missing father containing a letter and a strange device.

The letter says that with this device Takuya can travel to other dimensions. Reading it, he decides someone is playing a prank on him and puts the box away. But soon people begin hunting him to take the device, and Takuya realizes the package was no joke at all. Convinced that his father is alive but in serious danger he cannot escape on his own, Takuya resolves to do everything in his power to find him and see him again.