The chapters have been adapted into an original video animation (OVA) produced by Production I.G in 1998, and an anime series produced by Toei Animation, which began broadcasting in Japan in 1999. Since then, the still continuing series has aired over 674 episodes. Additionally, Toei has developed thirteen animated feature films, two OVA's, and five television specials. Several companies have developed various types of merchandising such as a trading card game, and a large number of video games. The manga series was licensed for an English language release in North America by Viz Media, in the United Kingdom by Gollancz Manga, and in Australia by Madman Entertainment. The entire anime series was first licensed by 4Kids, which due to poor reception, shifted in 2007 to Funimation for an English-language release in North America.