Kono Yo no Hate de Koi wo Utau Shoujo YU-NO
この世の果てで恋を唄う少女YU-NO, YU-NO: A girl who chants love at the bound of this world.
Takuya Arima is a young student whose father, a historian who has conducted various researches, disappeared recently. During a summer vacation Takuya receives a peculiar package from his missing father, along with a letter containing information about the existence of various parallel worlds. At first Takuya doesn't take it seriously, but soon he realizes that he possesses a device that allows him to travel to alternate dimensions. Is his father alive, after all? If so, where is he?