The anime adaption of Magic Knight Rayearth aired first on Japan's Yomiuri TV on October 17, 1994 and ended on November 27, 1995. The anime itself had two seasons, lasting 49 episodes altogether.
Differences in the anime
The first season remains mostly faithful to the first arc of the manga aside from the inclusion of the original character Inouva and a multitude of subplots, but the second season shows a rapid departure. Most notable differences are the creation of two anime only characters, Nova and Lady Debonair, who were born from the intense despair of Hikaru Shidou and the people of Cephiro respectively after the death of Princess Emeraude.
It is also revealed early on by the Rune Gods that the girls were summoned back to Cephiro by their own will, most notably Hikaru's as her strength of heart also allowed her to become the new Pillar, a position she rejects in a similar fashion to the manga.
A three-part OVA was released in Japan a few years after the end of the manga and anime. The OVA was renamed simply Rayearth, and its story was quite different from the original. The characters are all the same, but the relationships, places and events changed radically.
Here, we find that Hikaru, Umi and Fuu are already friends who go to the same school and will soon be leaving for high school. Suddenly, Mokona (now a strange fairy creature) appears before them. At the same time, strange monsters and wizards start to appear in the city of Tokyo. One of them is Clef, who tries to guide the three girls in order to let them become the Magic Knights, awaken their Mashin and fight against the evil wizards from Cephiro, who are trying to invade the human world.
In this version, Ferio, who is a sourcerer under Princess Emerude's command is not her brother, instead Eagle Vision is, who's also the main antagonist after he tricked Zagato to commit suicide in order to bring upon a false balance to Cephiro. He's ties to Autozam are non-exsistent in this version, as he is a citizen of Cephiro from the start. He would put a spell on Emeraude to convince her that Zagato is still alive, so that the sourcerers of Cephiro can continue to exist on Earth as the two worlds would soon merge and each sourcerer would battle against the Magic Knights.
Lantis is also introduced right away as being an ally to the Magic Knights and against Eagle's plans. The only other characters that are in the OVA are Ascot and Alcyone. None of the other characters are featured.