Also known as: Nakaimo: My Little Sister is Among Them! OVA, Nakaimo: My Sister is Among Them! OVA, One of Them Is My Younger Sister! OVA, Who is Imouto? OVA, Nakaimo OVA
The OVA adaptation of Kono Naka ni Hitori, Imouto ga Iru! (Nakaimo: My Little Sister is Among Them!) acts as the unaired episode 13 - titled "Ani, Imouto, Koibito" ("Big Brother, Little Sister, Lover") - for the 2012 TV anime series created by Studio Gokumi, based on a light novel series written by Hajime Taguchi and illustrated by CUTEG. This OVA episode features all of the heroines from the TV series.
Producers, official website and other details: ANN
. Search on: AniDB.