Original Video Animation-Format (2):- Most OVA titles run for 4 to 8 episodes, and some only have 1. They tend to have a complex and continuous plot [ citation needed], 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 happen to be released in parts. Release schedules vary: 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-storyto 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 Bleachand One Piece.