Story
OVA by bones — Summer 2018, 1 episode, Finished.
Bundled with the 5th volume of the Kekkai Sensen: Back 2 Back manga The OVA, which will have a duration of 24 minutes, will adapt two stories. The first story titled "Zapp Renfro Inga Oohou-juu!!" will adapt a chapter from volume four, while the second story, titled "Bakkaadio no Shizuku," will adapt a chapter from volume two.
Synopsis via AniList (English).
