what is a ova
Original video animation, abbreviated as OVA media, are animated films and series made specially for release in home video formats without prior showings on television or in theatres, though the first part of an OVA series may be broadcast for promotional purposes. OVA titles were originally made available on VHS, later becoming more popular on LaserDisc and eventually DVD. Starting in 2008, the term OAD began to refer to DVD releases published bundled with their source-material manga.