Sailor Moon is probably one of the most iconic 90s anime to have been released. And today, the first three seasons will be available for free on the show’s official YouTube channel.
Starting today, the channel will be releasing 10 episodes per week for a total of 127 episodes. It will continue on until July 17 ending with the last episode of the third season, Pretty Guardian Sailor Moon S.
— 劇場版「美少女戦士セーラームーンEternal」9.11公開🌙 (@sailor_movie) April 23, 2020
The release of these episodes is a move to promote the release of the upcoming two-part film, Pretty Guardian Sailor Moon Eternal The Movie. The upcoming movie will tackle the events that happened in the fourth season of the original anime which means watching the first three seasons will prepare you for it.
Unfortunately, since this is a local promotion, all the episodes uploaded will be in their original Japanese audio and without English subtitles. YouTube does have an auto-translate option but translation can be a bit too literal (Usagi, the name of the lead character, keeps being translated to Rabbit) and you might end up being more confused.