Owarimonogatari is part of the Monogatari anime series that was based on a light novel series by Nisio Isin. Owarimonogatari aired in Japan back in 2015. The next installment has been announced for summer 2017. On top of that. Starting next month the previous installments of Owarimonogatari will be reaired in Japan starting in April 2017.
— 西尾維新アニメプロジェクト (@nisioisin_anime) March 25, 2017