Kono Yo no Hate de Koi wo Utau Shoujo 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?
[Source: TLWiki via VNDB.org]