Unlike the second series, the card game (Duel Monsters) is not the sole focus of the show. New characters and plots, such as those relating to the four game masters, were added, and there are more occurrences of Seto Kaiba and Duel Monsters ( Magic and Wizards in the original Japanese manga) than in the corresponding manga. Also, Honda is Jonouchi's verbal sparring partner instead of his crony in Toei's anime. For instance, Miho is a "ditz" in the anime while in the manga she is a shy student librarian.
Finally, a minor character in the manga, Miho Nosaka, became a main character in the first series along with Yugi Mutou, Katsuya Jonouchi, Anzu Mazaki, and Hiroto Honda.
Also, the level of violence was reduced between the manga and the anime. Manga plots were re-written so that they could take up an entire episode's worth of time.
While this series is not directly connected to Yu-Gi-Oh! Duel Monsters (known internationally simply as Yu-Gi-Oh!, produced by Nihon Ad Systems and aired on TV Tokyo), both anime series are based on the Yu-Gi-Oh! manga.
The 27-episode series was produced by Toei Animation and aired on TV Asahi from April 4 to October 10, 1998. "King of Games", occasionally subtitled " A Game of Darkness" or " The Shadow Games", or unofficially referred to as "First Series" or "Season Zero" by fans, is the first anime adaptation of the Yu-Gi-Oh! manga series. "Crunchyroll To Stream English Subtitled "Yu-Gi-Oh! GX "". ^ "Crunchyroll Adds English-Subtitled Yu-Gi-Oh! Duel Monsters Anime"."Crunchyroll Adds "Yu-Gi-Oh!" Season 1 with English Subtitles". ^ "Official Japanese Yu-Gi-Oh! Episodes Removed from YouTube, Never to Return Again".^ "Removal of Yu-Gi-Oh! Episodes was due to Nonrenewal of Japanese Voice Actor's Contract by ADK".