Bundled with seventh Blu-ray/DVD volume of Kyoukai no Kanata.
Episode 0 happens two years prior to the TV series when the Nase siblings meet Akihito for the first time in a mission for Hiroomi. Mitsuki follows her brother on this mission and their goal is to subjugate Akihito.
AnimePiracy is a site to watch online anime like Kyoukai no Kanata: Shinonome (Dub) SUB online GoGoAnime, or you can even watch Kyoukai no Kanata: Shinonome (Dub) in HD quality just like KissAnime and 9Anime.