Due to anime's popularity, the other Sailor Scouts' appearances happened earlier

Sailor Moon editor Fumio “ Osabu ” Osano revealed in an interview with Comic Natalie that the manga side did not work closely with the anime's production team due to how quickly the anime was greenlit early in the manga's run. Because of the lack of time before the anime started airing, the manga side requested only that the anime not overtake the manga. Thus, the original plan for the anime's first 20 episodes was for them to feature Usagi having adventures by herself.

"For the manga, we had a rough outline for the plot prepared a year in advance," Osano explained. "The storyboards in the anime's first episodes are based on Takeuchi's sketches, so the anime matches the story and feel of the manga very well. Also, in the manga, each chapter introduces a new team member: Ami shows up in chapter 2, while Rei shows up in chapter 3. For the anime, it was originally decided to make Usagi have adventures by herself for about 20 episodes, and then meet up with Ami after that."

However, Osano went on, things didn't turn out quite as planned. " Toei requested that they show Ami and Rei in the opening in order to build up the popularity... So then when the first episode came out, there were rumors that more girls would be appearing. Toei and the TV station both decided that they had no choice but to change their plans to satisfy the viewers, so Ami appears in episode 8, while Rei appears in episode 10. Before we knew it, the anime had caught up to the manga."

Naoko Takeuchi launched the original magical girl team manga series in the shōjo monthly manga magazine Nakayoshi in 1991. A TV anime produced by Toei Animation first aired in Japan from 1992.

Another surprising reveal is that the anime was initially considered unsuccessful due to the fact it wasn't selling many toys, which could have threatened the continuation of the manga. "The manga was a hit from the beginning of its serialization. The first printing of volume 1 was 500,000 copies, and before we knew it, we had printed over a million copies. It had become a social phenomenon, so there was no way we were going to end it. But the anime wasn't selling many toys at first. Back then, anime that didn't look capable of selling toys usually got cancelled, and if that had happened, the manga may have had to conclude as well."

Osano also clarified in the interview that the reason why the manga took so long to get a digital release in Japan is because they wanted to line it up with the international release, which is slated to be published in 10 languages from July 1. Osano had been working on a digital manga release since 2013, when a complete set was released in Japan.

The rest of the interview discusses Osano's memories of the manga during its serialization. Osano closed the interview by saying that, in the wake of news that the Bishōjo Senshi Sailor Moon Eternal (Pretty Guardians Sailor Moon Eternal The MOVIE) film project is slated for 2020, the franchise will be getting "more developments" in the future.

Source: Comic Natalie