During the summer, Takuya Arima receives a package—from his missing father—detailing the existence of parallel universes. He investigates further and soon realizes that he’s been given the key to cross-dimensional time travel. Now, Takuya is forced to use this newfound tech to unravel the mystery of his father’s whereabouts and find out why those closest to him are keeping secrets.

[Source: Crunchyroll]

Completely new episode "26.5" included in the third Blu-ray box.