Original video animation , abbreviated as OVA media (and sometimes as OAV, original animated video), 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 OVA titles were originally made available on VHS, later becoming more popular on LaserDisc and eventually DVD.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 (original animation DVD) began to refer to DVD releases published bundled with their source-material manga.
Like anime made for television broadcast, OVAs sub-divide into episodes. OVA media (tapes, laserdiscs, or DVDs) usually contain just one episode each. Episode length varies from title to title: each episode may run from a few minutes to two hours or more. An episode length of 30 minutes occurs quite commonly, but no standard length exists. In some cases, the length of episodes in a specific OVA may vary greatly, for example in GaoGaiGar FINAL, the first 7 episodes last around 30 minutes, while the last episode lasts 50 minutes; the OVA Key the Metal Idol consists of 15 separate episodes, ranging in length from 20 minutes to nearly two hours each; The OVA Hellsing Ultimate had released 10 episodes, ranging from 42 minutes to 56 minutes. An OVA series can run anywhere from a single episode (essentially a direct-to-video movie) to dozens of episodes in length. Probably the longest OVA series ever made, Legend of the Galactic Heroes, spanned 110 main episodes and 52 gaiden (side stories) episodes.
Many popular series first appear animated as an OVA, and later grow to become television series or movies. Tenchi Muyo!, for example, began as an OVA but went on to spawn several TV series, three movies, and numerous other spin-offs. Producers make other OVA releases as sequels, side stories, music-video collections, or bonus episodes that continue existing as television series or films, such as Love Hina Again and Wolf’s Rain.
OVA titles generally have a much higher budget per episode than in a television series; therefore the technical quality of animation can generally surpass that in television series; occasionally it even equals that of animated movies.
OVA titles have a reputation for the detailed plots and character-development which can result from the greater creative freedom offered to writers and directors in comparison with other formats. This also allows for animated adaptations of manga to reflect their source material more faithfully. Since OVA episodes and series have no fixed conventional length, OVA directors can use however much time they like to tell the story. Time becomes available for significant background, character, and plot development. This contrasts with television episodes (which must begin and conclude in 22 to 26 minutes) and with films (which rarely last more than two hours). In the same way, no pressure exists to produce “filler content” to extend a short plot into a full television series. The producers of OVA titles generally target a specific audience, rather than the more mass-market audience of films and television series, or may feel less constrained by content-restrictions and censorship (such as for violence, nudity, and language) often placed on television series. For example, the Kissxsis OVA series generally contains more sexual themes than its television counterpart.