美少女戦士セーラームーン 1

Perfect as your first native manga

This is the first full volume of manga that I've read without quitting. It was a nice trek down memory lane too, as I grew up in the 90s and Sailor Moon was one of the first anime series I've ever watched.

The vocabulary is simple and pertains to everyday activities, many words are spelled using hiragana instead of their kanji forms and all kanji have furigana. Still, I had to look up a lot of words and made around ~300 Anki cards, so on average that's around a card per page.

It's a very solid choice as your first native manga. I would definitely continue with the series.

There's a few potential stumbling blocks with this series. The fantasy vocab will likely all be new to you, since it's stuff that certainly isn't taught in textbooks. The primary villains talk in Typical Anime Villain speech, which is archaic and, again, not taught in textbooks. But other than that, it's not all that difficult, and all kanji do have furigana.

To get the most benefit, I recommend watching the Sailor Moon Crystal anime alongside it. Because the new anime follows the manga so closely, if you read a manga chapter first and then watch the anime episode right after it'll be like you read the anime's script beforehand, so it makes understanding the episode that much easier and you get listening practice for the material you just read.

If you like Sailor Moon, reading the manga is a decent way to practice your Japanese. If you don't already love Sailor Moon, however, I doubt reading the manga will change your mind because the story is fairly predictable and shallow and the character development is pretty shallow (early on, anyway).