Format
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 is quite common, but this is by no means the rule. 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 lasted 50 minutes; the OVA Key the Metal Idol consists of 15 separate episodes, ranging in length from 20 minutes to nearly two hours each; as of 2012 the OVA Hellsing had released 9 episodes, ranging from 42 minutes to 56 minutes (it has yet to finish releasing the remaining episodes). An OVA series can run anywhere from an episode (essentially a direct-to-video movie) to dozens in length. Probably the longest OVA series ever made was Legend of the Galactic Heroes, which spanned 110 main episodes and 52 gaiden 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 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 and character/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, or language) often placed on television series. For example, the Kissxsis OAD series generally contains more sexual themes than its television counterpart.
Much OVA-production aims at an audience of male anime enthusiasts. Bandai Visual stated in a 2004 news release (for their new OVAs aimed at women) that about 50% of the customers who had bought their anime DVDs in the past fell into the category of 25- to 40-year-old men, with only 13% of purchasers women, even with all ages included. These statistics cover Bandai Visual anime DVDs in general, not just OVAs, but they show the general tendency at this point. Nikkei Business Publications also stated in a news-release that mainly 25- to 40-year-old adults bought anime DVDs. Few OVAs specifically target female audiences, but Earthian exemplifies the exceptions.
Usually one volume costs between 5800 to 9800 yen as of 2006, higher-priced than other anime DVDs, though some sell for less (Mobile Police Patlabor OVAs (1988) sold at 4800 yen per volume).
Some OVAs based on television series (and especially those based on manga) may provide closure to the plot – closure not present in the original series. The Rurouni Kenshin OVAs, to name one series, exemplified numerous aspects of OVAs; they were slightly based on chapters of the author Nobuhiro Watsuki's manga that had not been adapted into the anime TV series, had higher-quality animation, were much more violent, and were executed in a far more dark and realistic style than the TV episodes or the manga.
Dark realism featured in Masami Kurumada's famous manga Saint Seiya. The anime adapted two of the three arcs in Kurumada's manga - the project to adapt the third arc to the anime never started. As Kurumada had completed his manga in 1991, its third act was finally adapted to anime, releasing the episodes as OVAs, starting in 2003 and finishing in 2008, at last adapting Kurumada's manga completely to anime.
Most OVA titles run for 4 to 8 episodes. They tend to have a complex and continuous plot, best enjoyed if all episodes are viewed in sequence. This contrasts with television series, which generally have many short "mini-stories" that happen to be related somehow, rather than a unified plot. Many OVA titles can be thought of as "long films" that just so happen to be released in parts. Release schedules vary, as some series may progress as slowly as 1-2 episodes per year. Some OVA titles with a lengthy release-schedule ended up unfinished due to lack of fan support and sales.
Many one-episode OVAs exist as well. Typically, such an OVA provides a side-story to a popular TV series (Detective Conan OVAs). At an early stage in the history of the OVA (1980s) many one-episode OVAs appeared. Hundreds of manga that were popular but not enough to gain TV series were granted one-shot (or otherwise extremely short) OVA episodes. When these one-shot OVAs prove popular enough, a network can use the OVA as a pilot to an anime series, such as with Bleach.
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